程序设计与算法（一）C语言程序设计（北京大学MOOC）

第一周测验

1、 输出第二个整数

#include <iostream>  
#include <cstdio>
using namespace std;  
  
int main()
{
    int a,b,c;
    scanf("%d %d %d",&a,&b,&c);
    printf("%d",b);
    
    return 0;
}

2、字符菱形

#include <iostream>
#include <cstdio>
using namespace std;
#include <math.h>
int main() 
{
    char ch;
    cin>>ch;

    cout<<"  "<<ch<<endl;
    cout<<" "<<ch<<ch<<ch<<endl;
    cout<<ch<<ch<<ch<<ch<<ch<<endl;
    cout<<" "<<ch<<ch<<ch<<endl;
    cout<<"  "<<ch<<endl;

    return 0; 
}

3、打印ASCII码

#include <iostream>  
#include <cstdio>
using namespace std;  
  
int main()
{
    char ch;
    scanf("%c",&ch);
    printf("%d",ch);
    
    return 0;
}

4、打印字符

#include <iostream>  
#include <cstdio>
using namespace std;  
  
int main()
{
    int x;
    scanf("%d",&x);
    printf("%c",x);
    
    return 0;
}

5、整型数据类型存储空间大小

#include <iostream>  
#include <cstdio>
using namespace std;  
  
int main()
{
    int x;
    short y;
    printf("%d %d",sizeof(x),sizeof(y));
    
    return 0;
}

6、浮点型数据类型存储空间大小

#include <iostream>  
#include <cstdio>
using namespace std;  
  
int main()
{
    float x;
    double y;
    printf("%d %d",sizeof(x),sizeof(y));
    
    return 0;
}

第二周单元测验

1、对齐输出

#include <iostream>  
#include <cstdio>
using namespace std;  

int main()
{
    int a,b,c;
    scanf("%d %d %d",&a,&b,&c);
    printf("%8d %8d %8d",a,b,c);
    
    return 0;
}

2、输出保留12位小数的浮点数

#include <iostream>  
#include <cstdio>
using namespace std;  

int main()
{
    double x;
    scanf("%lf",&x);
    printf("%.12f",x);
    
    return 0;
}

3、空格分隔输出

#include <iostream>  
#include <cstdio>
using namespace std;  

int main()
{
    char ch;
    int x;
    float y;
    double z;
    scanf("%c",&ch);
    scanf("%d",&x);
    scanf("%f",&y);
    scanf("%lf",&z);
    printf("%c %d %f %lf",ch,x,y,z);
    
    return 0;
}

4、计算球的体积

#include <iostream>  
#include <cstdio>
using namespace std;  

int main()
{
    double r,v;
    scanf("%lf",&r);
    v = 4.0/3*3.14*r*r*r;
    printf("%.2lf",v);
    
    return 0;
}

5、大象喝水

#include <iostream>  
#include <cstdio>
using namespace std;  

int main()
{
    int h,r;
    scanf("%d%d",&h,&r);
    double x = 20*1000/(3.14159*r*r*h)+1;
    printf("%d",(int)x);
    
    return 0;
}

第三周测验

1、奇偶数判断

#include <iostream>
#include <cstdio> 
using namespace std;
  
int main()
{
    int n;
    cin>>n;
    if(n%2)cout<<"odd"<<endl;
    else cout<<"even"<<endl; 
    
    return 0;
}

2、求一元二次方程的根

#include <iostream>
#include <cmath>
#include <cstdio>
using namespace std;
int main( )
{
     double a,b,c,x1,x2,x3,x4;
     scanf("%lf%lf%lf",&a,&b,&c);
     x1 = (-b + sqrt(b*b-4*a*c))/(2*a)*1.0;
     x2 = (-b - sqrt(b*b-4*a*c))/(2*a)*1.0;
     x3 = -b / (2*a)*1.0;
     x4 = sqrt(4*a*c-b*b) / (2*a)*1.0;
     if(!x3)x3=0;
     if (b*b==4*a*c)
        printf("x1=x2=%.5f",x1);
     if (b*b>4*a*c)
         printf("x1=%.5f;x2=%.5f",x1,x2);
     if (b*b<4*a*c)
         printf("x1=%.5f+%.5fi;x2=%.5f-%.5fi",x3,x4,x3,x4);
     return 0;
}

3、点和正方形的关系

#include <iostream>
#include <cstdio> 
using namespace std;
  
int main()
{
    int x,y;
    cin>>x>>y;
    if(x>1||x<-1||y>1||y<-1)cout<<"no"<<endl;
    else cout<<"yes"<<endl;

    return 0;
}

4、苹果和虫子2

#include <iostream>
#include <cstdio> 
using namespace std;
  
int main()
{
    int n,x,y;
    cin>>n>>x>>y;
    int m = n-y/x-1;
    int k = n-y/x;
    if(m<0)m=0;
    if(k<0)k=0;
    if(y%x)cout<<m<<endl;
    else cout<<k<<endl;

    return 0;
}

5、简单计算器

#include <iostream>
#include <cstdio> 
using namespace std;
  
int main()
{
    int x,y;
    char ch;
    cin>>x>>y>>ch;
    switch(ch)
    {
        case '+':
            cout<<x+y<<endl;
            break;
        case '-':
            cout<<x-y<<endl;
            break;
        case '*':
            cout<<x*y<<endl;
            break;
        case '/':
            if(y==0)cout<<"Divided by zero!"<<endl;
            else cout<<x/y<<endl;
            break;
        default:
            cout<<"Invalid operator!"<<endl;     
    }
    
    return 0;
}

6、求整数的和与均值

#include <iostream>
#include <cstdio> 
using namespace std;
  
int main()
{
    int n,x;
    double sum=0;
    scanf("%d",&n);
    for(int i=0;i<n;++i)
    {
        scanf("%d",&x);
        sum+=x;
    }
    printf("%.0f %.5f",sum,sum/n);
    return 0;
}

7、整数序列的元素最大跨度值

#include <iostream>
#include <cstdio> 
using namespace std;
  
int main()
{
    int n,x,min=1000,max=0; 
    cin>>n;
    for(int i=0;i<n;++i)
    {
        cin>>x;
        if(x>max)max=x;
        if(x<min)min=x;
    }
    cout<<max-min<<endl;
    return 0;
}

8、奥运奖牌计数

#include <iostream>
#include <cstdio> 
using namespace std;
  
int main()
{
    int n,g,s,c,sum=0; 
    int sumg=0,sums=0,sumc=0;
    cin>>n;
    for(int i=0;i<n;++i)
    {    
        cin>>g>>s>>c;
        sumg+=g;
        sums+=s;
        sumc+=c;
    }
    sum=sumg+sums+sumc;
    cout<<sumg<<" "<<sums<<" "<<sumc<<" "<<sum<<endl;
    return 0;
}

9、乘方计算

#include <iostream>
#include <cstdio> 
using namespace std;
  
int main()
{
    long long a,n,sum=1;
    cin>>a>>n;
    for(int i=0;i<n;++i)
    {        
        sum =sum*a;
    }
    cout<<sum<<endl;
    return 0;
}

10、鸡尾酒疗法

#include <iostream>
#include <cstdio> 
using namespace std;
  
int main()
{
    int n,a,b,x,y;
    double tsub,osub;
    cin>>n>>a>>b;
    for(int i=0;i<n-1;++i)
    {    
        cin>>x>>y;
        tsub = 1.0*b/a-1.0*y/x;    
        osub = 1.0*y/x-1.0*b/a;
        if(tsub>0.05)
            cout<<"worse"<<endl;
        else if(osub>0.05)
            cout<<"better"<<endl;
        else 
            cout<<"same"<<endl;
    }
    
    return 0;
}

第四周测验

1、角谷猜想

#include <iostream>  
#include <cstdio>
using namespace std;  
 
int main()
{
    long long n;
    cin>>n;
    while(n!=1)
    {
        if(n%2)
        {
            cout<<n<<"*3+1="<<n*3+1<<endl;
            n = n*3+1;    
        }
        else
        {
            cout<<n<<"/2="<<n/2<<endl; 
            n = n/2;        
        }
    } 
    cout<<"End"<<endl;
    
    return 0;
}

2、正常血压

#include <iostream>  
#include <cstdio>
using namespace std;  
 
int main()
{
    int n, x, y;
    int thisCnt=0,maxCnt=0; 
    cin>>n;
    do
    {
        cin>>x>>y;
        if((x>=90&&x<=140)&&(y>=60&&y<=90))
        {
            thisCnt++;
            if(thisCnt>maxCnt)
            {
                maxCnt=thisCnt;
            }
        }
        else
        {
            thisCnt=0;
        }    
    } while(--n);
    
    cout<<maxCnt<<endl;
    
    return 0;
}

3、数字反转

#include <iostream>  
#include <cstdio>
using namespace std;  
 
int main()
{
    int t,ret=0;
    cin>>t;
    while(t)
    {
        ret=ret*10+t%10;
        t=t/10;    
    }
    cout<<ret<<endl;
    return 0;
}

4、求特殊自然数

#include <iostream>  
#include <cstdio>
using namespace std;  
 
int main()
{
    for(int a=1;a<7;++a)
    {
        for(int c=1;c<7;++c)
        {
            if(a+c*49==c+a*81)
            {
                cout<<a + c*49<<endl;
                cout<<c<<0<<a<<endl;
                cout<<a<<0<<c<<endl;
                break;     
            }         
        }     
    }            
    return 0;
}

5、雇佣兵

#include <iostream>  
#include <cstdio>
using namespace std;  
 
int main()
{
    int m,n,x;
    cin>>m>>n>>x;
    if(n<=m)
    {
        int t=0;
        while(x--)
        {    
            t+=n;
            if(t>=m)
            {
                t=0;
                n+=m/n;    
            }
        }    
    }
    cout<<n<<endl;
    return 0;
}

6、数字统计

#include <iostream>   
using namespace std;  

int main()  
{      
    int x,y;
    int cnt=0;
    cin>>x>>y;
    while(x<=y)
    {
        int temp = x;
        while(temp)
        {
            if(temp%10==2)cnt++;
            temp=temp/10;
        }
        x++;
    }
       cout<<cnt<<endl;
    return 0;  
}     

第五周测验

1、与指定数字相同的数的个数

#include <iostream>
using namespace std;
int main()
{
    int n,x;
    cin>>n;
    int a[n];
    for(int i=0;i<n;++i)
    {
        cin>>x;
        a[i]=x;
    } 
    int y,cnt=0;
    cin>>y;
    for(int i=0;i<n;++i)
    {
        if(a[i]==y)cnt++;
    }
    cout<<cnt<<endl;
    return 0;
}

2、陶陶摘苹果

#include <iostream>
using namespace std;
int main()
{
    int a[10],x;
    for(int i=0;i<10;++i)
    {
        cin>>x;
        a[i]=x;
    } 
    int h,cnt=0;
    cin>>h;
    h+=30;
    for(int i=0;i<10;++i)
    {
        if(a[i]<=h)cnt++;
    }
    cout<<cnt<<endl;
    return 0;
}

3、年龄与疾病

#include <iostream>
#include <cstdio>
using namespace std;
int main()
{
    int n,x;
    scanf("%d",&n);
    int a[n];     //c99
    for(int i=0;i<n;++i)
    {
        scanf("%d",&x);
        a[i]=x;
    } 
    int old18=0,old35=0,old60=0,old61=0;
    
    for(int i=0;i<n;++i)
    {
        
        if(a[i]<=18)old18++;
        else if(a[i]<=35)old35++;
        else if(a[i]<=60)old60++;
        else old61++;
    }
    double m = n;
    printf("%.2f%\n%.2f%\n%.2f%\n%.2f%\n",
        old18/m*100,old35/m*100,old60/m*100,old61/m*100);
    
    return 0;
}

4、校门外的树

#include <iostream> 
using namespace std;
int main()
{
    int L,M,a=0,s,e,tree[10001]={0};
    cin>>L>>M;
    for(;M>0;--M)
    {
        cin>>s>>e;
        for(;s<=e && s<=10000;++s) tree[s]=1;  
    }
    for(int i=0;i<=L;++i) a+=tree[i];
    a=L+1-a;
    cout<<a;
    return 0;
}

#include <iostream>
using namespace std;
int main() 
{
    int L,m;
    cin>>L>>m;
    int a[L+1]={0};
    while(m--)
    {
        int s,e;
        cin>>s>>e;
        for(int i=s;i<=e;++i)
        {
            a[i]=1;    
        }    
    }
    int cnt=0; 
    for(int i=0;i<L+1;++i)
    {
        if(a[i]==0)cnt++;    
    }    
    cout<<cnt<<endl;
    
    return 0;
}

5、计算鞍点

#include <iostream>
using namespace std;
int main() 
{
    int a[5][5],iMax[5]={0},maxI[5];
    for(int i=0;i<5;++i)
    {
        for(int j=0;j<5;++j)
        {
            cin>>a[i][j];
            if(a[i][j]>iMax[i])
            {
                iMax[i] = a[i][j];
                maxI[i] = j;
            }
        }
    }
    bool b = false;
    for(int i=0;i<5;++i)
    {
        int iMin = iMax[i];
        for(int j=0;j<5;++j)
        {
            if(a[j][maxI[i]]<iMin)
            {
                iMin=a[j][maxI[i]];
            }
        }
        if(iMin ==iMax[i])
        {
            b=true;
            cout<<i+1<<" "<<maxI[i]+1<<" "<<iMax[i]<<endl;
        }
    }
    if(!b) cout<<"not found"<<endl; 
    return 0;
}

6、图像模糊处理

#include <iostream>
#include <cmath>
using namespace std;
int main() 
{
    int n,m;
    cin>>n>>m;
    int a[n][m], b[n][m];
    for(int i=0;i<n;++i)
    {
        for(int j=0;j<m;++j)
        {
            cin>>a[i][j];
            b[i][j]=a[i][j];
        }
    }
    for(int i=1;i<n-1;++i)
    {
        for(int j=1;j<m-1;++j)
        {
            double x = (a[i][j]+a[i][j-1]+a[i][j+1]+a[i-1][j]+a[i+1][j])/5.0;
            b[i][j] = round(x);
        }
    }
    
    for(int i=0;i<n;++i)
    {
        for(int j=0;j<m;++j)
        {    
            cout<<b[i][j];
            if(j<m-1)cout<<" ";    
        }
        cout<<endl;
    }
    
    return 0;
}

7、矩阵转置

#include <iostream>
using namespace std;
int main() 
{
    int n,m;
    cin>>n>>m;
    int a[n][m];
    for(int i=0;i<n;++i)
    {
        for(int j=0;j<m;++j)
        {
            cin>>a[i][j];
        }
    }
    
    for(int i=0;i<m;++i)
    {
        for(int j=0;j<n;++j)
        {    
            cout<<a[j][i];
            if(j<n-1)cout<<" ";    
        }
        cout<<endl;
    }
    
    return 0;
}

第六周测验

1、Pell数列

# include<stdio.h>
int b[1000010]={0,1,2}; 
int  main()
{   
    int n,i,k;
    scanf("%d",&n);
    for(i=3;i<1000000;++i)
    {   
        b[i]=(2*b[i-1]+b[i-2])%32767;
    }        
    for(i=0;i<n;++i)
    {
        scanf("%d",&k);
        printf("%d\n",b[k]);
    }
    return 0;
} 

#include<iostream>  
#include<cstdio>   
using namespace std;  

long long Pell(int k)
{  
    long long a1=1,a2=2,a3;
    if(k==1)return a1;
    if(k==2)return a2;
    k-=2;
    while(k--)
    {
        a3=a1+2*a2;
        a1=a2;
        a2=a3;
        a1%=32767;
        a2%=32767;
        a3%=32767;
    }
    return a3;
}  
int main()  
{  
    int n;  
    cin>>n;  
    while(n--)
    {
        int k;
        cin>>k;
        cout<<Pell(k)<<endl;
    }
}

2、求最大公约数问题

#include<iostream>
#include<cstdio>
using namespace std;
int gcd(int a,int b)
{
    while(a%b)
    {
        int temp;
        temp=a;
        a=b;
        b=temp%b;    
    }
    return b;
}
 
int main()
{
    int a,b;
    cin>>a>>b;
    cout<<gcd(a,b);
  
    return 0;
}

3、第i位替换

#include <iostream>
using namespace std;

int bitManipulation1(int n, int m, int i) {
return (n&(~(1<<i)) | ((m >> i)&1)<< i);
}

int main() {
    int n, m, i, t;
    cin >> t;
    while (t--) { 
        cin >> n >> m >> i;
        cout << bitManipulation1(n, m, i) << endl;
    }
    return 0;
}

4、第i位取反

#include <iostream>
using namespace std;

int bitManipulation2(int n, int i) {
return n^(1<<i);
}

int main() {
    int t, n, i;
    cin >> t;
    while (t--) {
        cin >> n >> i;
        cout << bitManipulation2(n, i) << endl;
    }
    return 0;
}

5、左边i位取反

#include <iostream>
using namespace std;

int bitManipulation3(int n, int i) {
return n^(0xffffffff<<(32-i));
}

int main() {
    int t, n, i;
    cin >> t;
    while (t--) {
        cin >> n >> i;
        cout << bitManipulation3(n, i) << endl;
    }
    return 0;
}

第七周测验

1、统计数字字符个数

#include<iostream>
using namespace std;

int main(){
    char str[255]="";
    gets(str);
    int i=0,cnt=0;
    while(str[i]!='\0')
    {
        if(isdigit(str[i])) cnt++;
        i++;
    }
    cout<<cnt<<endl;
    return 0;
}

2、找第一个只出现一次的字符

#include<iostream>
using namespace std;

int main()
{
    char str[100000]="";
    char cc=' ';
    int ch[26]={0};
    gets(str);
    for(int i=0;str[i];++i)
    {
        ch[str[i]-'a']++;
    }

    for(int i=0;str[i];++i)
    {
        if(ch[str[i]-'a']==1)
        {
            cc=str[i];
            break;
        }        
    }
    if(cc==' ')cout<<"no";
    else cout<<cc<<endl;
    return 0;
}

3、石头剪子布

#include<iostream>
using namespace std;

int main()
{
    int n;
    cin>>n;
    while(n--)
    {
        string str1,str2;
        cin>>str1>>str2;
        
        if(str1==str2)cout<<"Tie"<<endl;
        else if(str1=="Rock"&&str2=="Scissors"||str1=="Paper"&&str2=="Rock"
            ||str1=="Scissors"&&str2=="Paper") cout<<"Player1"<<endl;    
        else cout <<"Player2"<<endl; 
    }
    return 0;
}

4、最长最短单词

#include <iostream> 
#include <cstring> 
using namespace std; 

int main() 
{  
    char str[200*100]="",word[100]="";
    char minWord[100]="",maxWord[100]=""; 
    int min=100,max=0;
    gets(str);
    int i=0;
    while(str[i]!='\0')
    {
        while(!(str[i]>=65&&str[i]<=90||str[i]>=97&&str[i]<=122)) ++i;
        if(!str[i]) break;
        int j=0;
        while(str[i]>=65&&str[i]<=90||str[i]>=97&&str[i]<=122)
        {
            word[j]=str[i];
            ++j,++i;
        }
        word[j]='\0';
        int len = strlen(word);
        if(len>max)
        {
            max=len;
            strcpy(maxWord,word);
        }
        if(len<min)
        {
            min=len;
            strcpy(minWord,word);
        }    
    }
    cout<<maxWord<<endl;
    cout<<minWord<<endl; 
    return 0; 
} 

5、密码翻译

# include<stdio.h>

int  main()
{   
    char ch[100]="";
    gets(ch);
    int i=0;
    while(ch[i]!='\0')
    {
        if(ch[i]>='a'&&ch[i]<='z')
        {
            int c = ch[i]+1;
            if(c>122)c-=26;
            printf("%c",c);
        }
        else if(ch[i]>='A'&&ch[i]<='Z')
        {
            int c = ch[i]+1;
            if(c>90)c-=26;
            printf("%c",c);
        }        
        else printf("%c",ch[i]);
        i++;
    }
    return 0;
} 

第九周测验

1、指针练习：输出Hello

#include <iostream>
using namespace std;
int main() {
    char s[] = "Hello";  
    char * p;
    for(p=s;*p;++p)
        cout << * p ;
    return 0;
}

2、指针练习:输出Tesla

#include <iostream>
using namespace std;
void Print(const char * p1, const char * p2) 
{  
    for(;p1<p2;++p1)     
        cout << * p1;
}
int main()  
{
    const char * s = "Tesla123";
    Print(s,s+5);
    cout << endl;
    Print(s,s+3);
    cout << endl;
    
    return 0;
}

3、指针练习：ForEach

#include <iostream>
using namespace std;

void ForEach(void * a, int width, int num,
void (*f)(void *)
)

{
    for(int i = 0;i < num; ++i) 
        f((char*)a+width*i);
}

void PrintSquare(void * p)
{
    int * q = (int*)p;
    int n = *q;
    cout << n * n << ",";
}
void PrintChar(void * p) {
    char * q = (char*)p;
    cout << *q << ",";
}
int main()
{
    int a[5] = {1,2,3,4,5};
    char s[] = "hello!";
    ForEach(a,sizeof(int),5,PrintSquare); 
    cout << endl;
    ForEach(s,sizeof(char),6,PrintChar);
    return 0;
}

4、指针练习：Memcpy之一

#include <iostream>
using namespace std;
void Memcpy(char * src,char * dest,int n)
{
char *pdest = (char *)dest;
    char *psrc =(char *)src;
    for(int i=0;i<n;++i)
    {
        *(pdest+i)=*(psrc+i); 
    }
}
int Strlen(char * s)
{    
    int i;
    for( i = 0; s[i]; ++i);
    return i;
}
int main()  
{
    int a;
    char s1[30];
    char s2[30];
    int t;
    cin >> t;
    for(int i = 0;i < t; ++i) {
        cin >> a;
        int b = 99999999;
        Memcpy((char*)&a,(char *) &b,sizeof(int));
        cout << b << endl;
    }
    for(int i = 0;i < t; ++i) {
        cin >> s1;
        Memcpy(s1,s2,Strlen(s1)+1);
        cout << s2 << endl;
    }
    return 0;
}

 5、指针练习：double

#include <iostream>
using namespace std;

void Double(int * p, int n)
{
    for(int i = 0;i < n; ++i)
        p[i] *= 2;
}


int main()
{
    int a[3][4] = { { 1,2,3,4},{5,6,7,8},
                    { 9,10,11,12 } };
    
    Double(a[1],6);
    for(int i = 0;i < 3; ++i) {
        for(int j = 0; j < 4; ++j)
            cout << a[i][j] << ",";
        cout << endl; 
    }
    
    return 0;
}

6、指针练习：Memcpy之二

#include <iostream>
using namespace std;
void Memcpy( void * src, void * dest, int size)
{
    char *pdest = (char*)dest;
    char *psrc = (char *)src;
    char p[size];
    for(int i=0;i<size;++i)
    {
        p[i]=*(psrc+i);
    }
    for(int i=0;i<size;++i)
    {
        *(pdest+i)=p[i];
    }
}

void Print(int * p,int size)
{
    for(int i = 0;i < size; ++i)
        cout << p[i] << ",";
    cout << endl;
}

int main()
{
    int a[10];
    int n;
    cin >> n;
    for(int i = 0;i < n; ++i)
        cin >> a[i];
    int b[10] = {0};
    Memcpy(a,b,sizeof(a));
    Print(b,n);
    
    int c[10] = {1,2,3,4,5,6,7,8,9,10};
    Memcpy(c,c+5,5*sizeof(int)); //将c的前一半拷贝到后一半 
    Print(c,10);

    char s[10] = "123456789";
    Memcpy(s+2,s+4,5); //将s[2]开始的5个字符拷贝到s[4]开始的地方 
    cout << s << endl;
    
    char s1[10] = "123456789";
    Memcpy(s1+5,s1+1,4); //将s1[5]开始的4个字符拷贝到s1[1]开始的地方 
    cout << s1 << endl;
    
    
    return 0;
}

7、指针练习：MyMax

#include <iostream>
using namespace std;
void *MyMax(void *a,unsigned int size,int n,int (*f)(void *,void *))
{
    void* max = (char*)a;
    for(int i=1; i<n; i++) 
    {
        if(f(max, ((char*)a)+i*size)<0) max = ((char*)a)+i*size;      
    }
    return max;
}
int Compare1(void * n1,void * n2)
{
    int * p1 = (int * )n1;
    int * p2 = (int * )n2;
    return ((*p1)%10) - ((*p2)%10);
}
int Compare2(void * n1,void * n2)
{
    int * p1 = (int * )n1;
    int * p2 = (int * )n2;
    return *p1 - *p2;
}
#define eps 1e-6
int    Compare3(void * n1,void * n2)
{
    float * p1 = (float * )n1;
    float * p2 = (float * )n2;
    if( * p1 - * p2 > eps)
        return 1;
    else if(* p2 - * p1 > eps)
        return -1;
    else
        return 0; 
}

int main()
{
    int t;
    int a[10];
    float d[10];
    cin >> t;
    while(t--) {
        int n;
        cin >> n;
        for(int i = 0;i < n; ++i)
            cin >> a[i];
        for(int i = 0;i < n; ++i)
            cin >> d[i];
        int * p = (int *) MyMax(a,sizeof(int),n,Compare1);
        cout << * p << endl;
        p = (int *) MyMax(a,sizeof(int),n,Compare2);
        cout << * p << endl;
        float * pd = (float * )MyMax(d,sizeof(float),n,Compare3);
        cout << * pd << endl;
    }
    return 0;
}

8、指针练习：指向指针的指针

#include <iostream>
using namespace std;
int main()
{
    int x,y,z;
    x = 10;
    y = 20;
    z = 30;
    
    int * a[3]  = { &x, &y,&z};
    for(int **p=a;p < a + 3; ++p) 
            cout<< * (*p) << endl;
    return 0;    
}

9、指针练习：SwapMemory

#include <iostream>
using namespace std;
void SwapMemory(void * m1,void * m2, int size)
{
    char *x = (char*)m1;
    char *y = (char*)m2;
    for(int i=0;i<size;++i)
    {
        char temp;
        temp=*(x+i);
        *(x+i)=*(y+i);
        *(y+i)=temp;
    }
}

void PrintIntArray(int * a,int n)
{
    for(int i = 0;i < n; ++i)
        cout << a[i] << ",";
    cout << endl;
}

int main()
{
    int a[5] = {1,2,3,4,5};
    int b[5] = {10,20,30,40,50};
    SwapMemory(a,b,5 * sizeof(int));
    PrintIntArray(a,5);
    PrintIntArray(b,5);
    char s1[] = "12345";
    char s2[] = "abcde";
    SwapMemory(s1,s2,5);
    cout << s1 << endl;
    cout << s2 << endl;
    return 0;
}

第十周测验

1、成绩排序

#include<iostream>
#include<cstring>
using namespace std;

struct StudSore{
    int psore;
    //char sname[20];
    string sname;
};

int main()
{    
    //StudSore ssore[25], tmp;
    int n, i, j;
    cin>>n;
    StudSore ssore[n], tmp;
    for(i=0; i<n; i++)
        cin>>ssore[i].sname>>ssore[i].psore;
    for(i=0; i<n-1; i++)
    {
        int max=i;
        for(j=i+1; j<n; j++){
            if((ssore[max].psore<ssore[j].psore)||
            (ssore[max].psore==ssore[j].psore&&ssore[max].sname>ssore[j].sname))
                max=j;
        }            
        tmp=ssore[i];
        ssore[i]=ssore[max];
        ssore[max]=tmp;                    
    }        
    for(i=0; i<n; i++)
        cout<<ssore[i].sname<<" "<<ssore[i].psore<<endl;
}

2、分数线划定

#include <iostream> 
#include <cstring> 
using namespace std; 

struct student
{
    unsigned str;
    int achivement;
};

void BubbleSort(student stu[] ,int size) 
{  
    for(int i = size-1;i > 0; --i )  
    {        
        for(int j = 0; j < i; ++j)
        {   
            if( stu[j].achivement < stu[j+1].achivement||
                ( stu[j].achivement == stu[j+1].achivement&&
                     stu[j].str> stu[j+1].str )
              )
            {     
                student temp = stu[j];     
                stu[j] = stu[j+1];    
                stu[j+1] = temp; 
            }      
        }
    } 
} 

int main() 
{  
    int n,m;
    cin>>n>>m;
    struct student stu[n];
    for(int i=0;i<n;++i)
    {
        cin>>stu[i].str>>stu[i].achivement;
    }
    BubbleSort(stu,n);
    m *=1.5;
    while(stu[m-1].achivement==stu[m].achivement)m++;
    cout<<stu[m-1].achivement<<" "<<m<<endl;
    for(int i=0;i<m;++i)
    {
        cout<<stu[i].str<<" "<<stu[i].achivement<<endl;
    }
    
    return 0; 
} 

3、病人排队

#include <iostream> 
#include <cstring> 
using namespace std; 

struct student
{
    string str;
    int achivement;
};

void BubbleSort(student stu[] ,int size) 
{  
    for(int i = size-1;i > 0; --i )  
    {        
        for(int j = 0; j < i; ++j)
        {   
            if(stu[j].achivement < stu[j+1].achivement) 
            { 
                student temp = stu[j];     
                stu[j] = stu[j+1];    
                stu[j+1] = temp; 
            }      
        }
    } 
} 

int main() 
{  
    int n;
    cin>>n;
    struct student stu[n],stu1[n];
    for(int i=0;i<n;++i)
    {
        cin>>stu[i].str>>stu[i].achivement;
        stu1[i]=stu[i];
    }
    BubbleSort(stu1,n);
    for(int i=0;i<n;++i)
    {
        if(stu1[i].achivement>=60)cout<<stu1[i].str<<endl;    
    }
    for(int i=0;i<n;++i)
    {
        if(stu[i].achivement<60)cout<<stu[i].str<<endl;
    }
    
    return 0; 
} 

4、mysort

#include <iostream>
using namespace std;
struct A {
    int nouse1;
    int nouse2;
    int n;
};
void mysort(void* a, int n, int w, int(*compare)(const void* , const void* )) 
{
    for(int i=n-1; i>=0; --i)
    {
        for(int j=0; j<i; ++j) 
        {
            char* p1 = (char*)a+j*w;
            char* p2 = (char*)a+j*w+w;
            if(compare(p1,p2) > 0) 
            {
                for(int k=0; k<w; ++k) 
                {
                    char tmp = p1[k];
                    p1[k] = p2[k];
                    p2[k] = tmp;
                }
            }
        }
    }       
}
int MyCompare1( const void * e1,const void * e2) 
{
    int * p1 = (int * ) e1;
    int * p2 = (int * ) e2;
    return * p1 - * p2;
}
int MyCompare2( const void * e1,const void * e2) 
{
    int * p1 = (int * ) e1;
    int * p2 = (int * ) e2;
    if( (* p1 %10) - (* p2 % 10))
        return (* p1 %10) - (* p2 % 10);
    else
        return * p1 - * p2;
}
int MyCompare3( const void * e1,const void * e2) 
{
    A * p1 = (A*) e1;
    A * p2 = (A*) e2;
    return p1->n - p2->n;
}
int a[20];
A b[20];
int main ()
{    
    int n;
    while(cin >> n) {
        for(int i = 0;i < n; ++i) {
            cin >> a[i];
            b[i].n = a[i];
        }
        mysort(a,n,sizeof(int),MyCompare1);
        for(int i = 0;i < n; ++i) 
            cout << a[i] << "," ;
        cout << endl;
        mysort(a,n,sizeof(int),MyCompare2);
        for(int i = 0;i < n; ++i) 
            cout << a[i] << "," ;
        cout << endl;
        mysort(b,n,sizeof(A),MyCompare3);
        for(int i = 0;i < n; ++i) 
            cout << b[i].n << "," ;
        cout << endl;
    }
    return 0;
}

5、从字符串中取数

#include <iostream>
#include <iomanip>
using namespace std;
double GetDoubleFromString(char * str)
{
    static char * start ; 
    if(str) start = str;
    //非数字
    for(; *start &&(*start<'0' ||*start>'9') ; ++start );
    //double    
    char * q = start;
    //double 
    for(; *start>='0' &&*start<='9' || *start=='.'; ++start );
    //避免科学计数法 
    if( * start) * start = 'c';
    
    return atof(q);
}

int main()
{
    char line[300];
    while(cin.getline(line,280)) {
        double n;
        n = GetDoubleFromString(line);
        while( n > 0) {
            cout << fixed << setprecision(6) << n << endl;
            n = GetDoubleFromString(NULL);
        }
    }
    return 0;
}

第十一周测验

1、派

#include<cstdio>
#include<cmath>
#include<algorithm>
using namespace std;

const double PI=acos(-1.0);
const int maxn = 10000+10;
double a[maxn];

bool can(double s,int n,int f) 
{
    int cnt=0;
    for(int i=1;i<=n;i++) cnt += floor(a[i]/s);
    return cnt>=f+1;        //f+1 自己 
}

int main() 
{
    int n,f;
    scanf("%d%d",&n,&f);
    double L=0,R=0;
    for(int i=1;i<=n;i++) 
    {
        scanf("%lf",&a[i]);
        a[i]=PI*a[i]*a[i];
        R=max(a[i],R);
    }
    double mid;
    while(R-L>1e-5) 
    {
        mid=L+(R-L)/2;
        if(can(mid,n,f)) L=mid;
        else R=mid;
    }
    printf("%.3lf\n",L);
    return 0;
}

2、月度开销

#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
using namespace std;

int w[100010],ans;
int tot,l,r,mid;

bool f(int x,int n,int m)
{
    int k=0,num=0;
    for (int i=1;i<=n;i++)
    {
        if (w[i]>x) return false;
        if (k+w[i]>x) k=w[i],num++;
        else k+=w[i];
    }
    num++;//最后若干天也要划分为一个月，所以num++
    if (num<=m) return true;
    else return false;
}
int main()
{
    int n,m;
    cin>>n>>m;
    for (int i=1;i<=n;i++) 
    {
        cin>>w[i];
        tot+=w[i];
    }
    r=tot;
    while (l<=r)
    {
        mid=(r+l)/2;
        if (f(mid,n,m)) ans=mid,r=mid-1;
        else l=mid+1;
    }
    cout<<ans;
}

3、Aggressive cows

#include<iostream>
#include<algorithm>
#include<stdio.h>
#include<string.h>
using namespace std;
const int MAX = 100010;
int a[MAX],n,m;

bool C(int d)
{
    int t = a[0],count = 1;
    for(int i = 1;i < n;i ++)
    {
        if(a[i] - t >= d)
        {
            count ++;
            t=a[i];
            if(count >= m)
                return true;
        }
    }
    return false;
}

int solve()
{
    int x = 0,y = a[n-1] - a[0];
    while(x <= y)
    {
        int mid=(x+y)/2;
        if(C(mid))
            x=mid + 1;
        else
            y=mid - 1;
    }
    return x - 1;
}

int main()
{
    while(~scanf("%d%d",&n,&m))
    {
        for(int i = 0;i < n;i ++)
        scanf("%d",&a[i]);
        sort(a,a+n);
        printf("%d\n",solve());
    }
    return 0;
}

第十二周测验

1、sort简单题

#include <iostream>
#include <algorithm>
using namespace std;

int main()
{
    int a[8] = {6,5,14,23,2,9,87,10 };
    sort(a+1,a+7,greater<int>());
    for(int i = 0;i < 8; ++i)
        cout << a[i] << "," ; 
    return 0;
}

2、还是sort简单题

#include <iostream>
#include <algorithm>
#include <cmath>
using namespace std;

struct Point{
    int x;
    int y;
};
struct Rule1
{
    bool operator() (const int &a1,const int &a2)
    {
        if(a1%10==a2%10)
            return a1>a2;
        return a1%10<a2%10;
    }
};
struct Rule2
{
    bool operator() (const Point &a1,const Point &a2)
    {
        double dis1 = sqrt (abs(a1.x)*abs(a1.x)+abs(a1.y)*abs(a1.y));
        double dis2 = sqrt (abs(a2.x)*abs(a2.x)+abs(a2.y)*abs(a2.y));
        double d = dis1-dis2;
        double eps = 1e-6;
            
        if(d>-eps&&d<eps&&(a1.x)!=(a2.x)) 
            return a1.x<a2.x;
        else if(d>-eps&&d<eps&&(a1.x)==(a2.x))
            return a1.y<a2.y; 
        return dis1<dis2;    
    }
};
int main()
{
    int a[8] = {6,5,55,23,3,9,87,10 };
    sort(a,a+8,Rule1());
    for(int i = 0;i < 8; ++i)
        cout << a[i] << "," ; 
    cout << endl;
    Point ps[8] = {{1,0},{0,1},{0,-1},{-1,0},{1,-1},{1,1},{2,0},{-2,0} } ;
    sort(ps,ps+8,Rule2());
    for(int i = 0;i < 8; ++i)
        cout << "(" << ps[i].x << "," << ps[i].y << ")"; 
    return 0;
}

3、Set

#include <iostream>
#include <set>
#include <string>
using namespace std;

int main()
{  
    multiset<int> mst;
    set<int> st;//保存num，因为multiset删除了就没num了 
    string str;
    int n,num;
   
    cin >> n;
    while(n--)
    {
        cin >> str >> num;
        if(str=="add")
        {
            mst.insert(num);
            st.insert(num);
            cout << mst.count(num) << endl;
        }
        else if(str=="del") 
        {
            cout << mst.count(num) << endl;
            mst.erase(num);
        }
        else if(str=="ask") 
        {
            if (st.find(num)==st.end())//判断num是否加入过 
                cout << "0 0" << endl;
            else
            {
                cout <<"1 ";
                cout << mst.count(num) << endl;
            }   
        }
    }
    return 0;
}

4、热血格斗场

# include <iostream>  
# include <cstdio>  
# include <map>  
# include <cmath>  
  
using namespace std;  
  
map<int,int> member;  
  
void match(int power)  
{  
    int lower = 0;  
    int upper = 0;  
    map<int,int>::iterator i;  
    map<int,int>::iterator j;  
    map<int,int>::iterator k;  
    i = member.find(power);   
    if ( i == member.begin() )  
    {  
        j = i;  
        j++;  
        printf("%d %d\n",i->second,j->second);  
    }  
    else  
    {  
        j = i;
        k = i;  
        j++;  
        upper = j->first - i->first;   
        k--;  
        lower = i->first - k->first;  
        if ( lower <= upper )  
        {  
            printf("%d %d\n",i->second,k->second);  
        }  
        else   
        {  
            printf("%d %d\n",i->second,j->second);  
        }  
    }  
}  
   
int main()  
{  
    int n = 0;  
    int id = 0;  
    int power = 0;  
    cin >> n;  
    member.insert(make_pair(1000000000,1));  
    for ( int i = 0; i < n; i++ )  
    {  
        scanf("%d%d",&id,&power);  
        member.insert(make_pair(power,id));  
        match(power);  
    }  
    return 0;  
}  

第十三周测验

冷血格斗场

#include<cstdio>  
#include<iostream>  
#include<algorithm>   
#include<map>   
using namespace std;  
const int maxn=100005;   
map<int,int>mp;
int main()  
{  
    int n,id,power; 
    scanf("%d",&n);  
    mp[1000000000]=1;  //facer  
    for(int i=1;i<=n;i++)  
    {  
        scanf("%d%d",&id,&power);  
        map<int,int>::iterator it;  
        it=mp.lower_bound(power);    
        if(it==mp.end())  it--;  
        int t=abs(it->first-power);  
        int idx=it->second;  
        if(it!=mp.begin())  
        {  
            it--;  
            if(abs(it->first-power)<t || (abs(it->first-power)==t && it->second<idx))  
            idx=it->second;  
        }  
        printf("%d %d\n",id,idx);  
        it=mp.find(power);  
        if(it==mp.end() || it->second>id)   mp[power]=id; 
    }  
    return 0;  
}