实验三

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#include <stdio.h>
#include <stdlib.h>

int power(int x, int n);    // 函数声明

int main() {
    int x, n;
    int ans;

    while(printf("Enter x and n: "), scanf("%d%d", &x, &n) != EOF) {
        ans = power(x, n);  // 函数调用
        printf("n = %d, ans = %d\n\n", n, ans);
    }
    
    system("pause");
    return 0;
}

// 函数定义
int power(int x, int n) {
    int t;

    if(n == 0)
        return 1;
    else if(n % 2)
        return x * power(x, n-1);
    else {
        t = power(x, n/2);
        return t*t;
    

#include <stdio.h>
#include<stdlib.h>

char score_to_grade(int score);  // 函数声明

int main() {
    int score;
    char grade;

    while(scanf("%d", &score) != EOF) {
        grade = score_to_grade(score);  // 函数调用
        printf("分数: %d, 等级: %c\n\n", score, grade);
    }

    system("pause");
    return 0;
}

// 函数定义
char score_to_grade(int score) {
    char ans;

    switch(score/10) {
    case 10:
    case 9:   ans = 'A'; break;
    case 8:   ans = 'B'; break;
    case 7:   ans = 'C'; break;
    case 6:   ans = 'D'; break;
    default:  ans = 'E';
    }

    return ans;
}

#include <stdio.h>
#include <stdlib.h>

int sum_digits(int n);  // 函数声明

int main() {
    int n;
    int ans;

    while(printf("Enter n: "), scanf("%d", &n) != EOF) {
        ans = sum_digits(n);    // 函数调用
        printf("n = %d, ans = %d\n\n", n, ans);
    }

    system("pause");
    return 0;
}

// 函数定义
int sum_digits(int n) {
    int ans = 0;

    while(n != 0) {
        ans += n % 10;
        n /= 10;
    }

    return ans;
}

#include <stdio.h>
#include <stdlib.h>

int power(int x, int n);    // 函数声明

int main() {
    int x, n;
    int ans;

    while(printf("Enter x and n: "), scanf("%d%d", &x, &n) != EOF) {
        ans = power(x, n);  // 函数调用
        printf("n = %d, ans = %d\n\n", n, ans);
    }
    
    system("pause");
    return 0;
}

// 函数定义
int power(int x, int n) {
    int t;

    if(n == 0)
        return 1;
    else if(n % 2)
        return x * power(x, n-1);
    else {
        t = power(x, n/2);
        return t*t;
    }
}

#include <stdio.h>
#include <stdlib.h>
int is_prime(int n);

int main(){
    int n;
    int s=0;
    int ans1,ans2;
    for(n=1;n<=98;n++){
        ans1=is_prime(n);
        ans2=is_prime(n+2);
        if(ans1==1 && ans2==1){
            printf("%d %d\n",n,n+2);
            s+=1;
        }
    }
    printf("100以内的孪生素数共有%d个",s);
    system("pause");
    return 0;
}

int is_prime(int n){
    int i;
    if(n==1)
        return 0;
    for(i=2;i<=n/2;i++){
        if(n%i==0)
            return 0;
    }
    return 1;
}

#include <stdio.h>
#include <stdlib.h>
void hanoi(unsigned int n,char from,char temp,char to);
int moveplate(unsigned int n,char from,char to);
int s;

int main(){
    unsigned int n;
    while(scanf("%u",&n)!=EOF){
        hanoi(n,'A','B','C');
        printf("一共移动了%d次.\n",s);
    s=0;
    }
    system("pause");
    return 0;
}

void hanoi(unsigned int n,char from,char temp,char to)
{
    if(n==1){
        moveplate(n,from,to);
    }
    else{
        hanoi(n-1,from,to,temp);
        moveplate(n,from,to);
        hanoi(n-1,temp,from,to);
    }
    s+=1;
}

int moveplate(unsigned int n,char from,char to)
{
    printf("%u:%c-->%c\n",n,from,to);
}

#include <stdio.h>
#include <stdlib.h>
int func(int n, int m);   // 函数声明

int main() {
    int n, m;
    int ans;

    while(scanf("%d%d", &n, &m) != EOF) {
        ans = func(n, m);   // 函数调用
        printf("n = %d, m = %d, ans = %d\n\n", n, m, ans);
    }

    system("pause"); 
    return 0;
}

int func(int n,int m){
    int ans1=1,ans2=1,ans;
    int i,j;
    if(n<m)
        return 0;
    else
        for(i=n;i>=(n-m+1);i--)
            ans1*=i;
        for(j=1;j<=m;j++)
            ans2*=j;
        ans=ans1/ans2;
}

#include <stdio.h>
#include <stdlib.h>
int func(int n, int m);   // 函数声明

int main() {
    int n, m;
    int ans;

    while(scanf("%d%d", &n, &m) != EOF) {
        ans = func(n, m);   // 函数调用
        printf("n = %d, m = %d, ans = %d\n\n", n, m, ans);
    }

    system("pause"); 
    return 0;
}

int func(int n,int m){
    int ans;
    if(n<m)
        return 0;
    else if (m==0)
        return 1;
    else if(m==1)
        ans=n;
    else
        ans=func(n-1,m)+func(n-1,m-1);
    return ans;
}

#include <stdio.h>
#include <stdlib.h>

int gcd(int a, int b, int c);

int main() {
    int a, b, c;
    int ans;
    while (scanf("%d%d%d", &a, &b, &c)!= EOF) {
        ans = gcd(a, b, c);  
        printf("最大公约数:%d\n\n", ans);
    }
    system("pause");
    return 0;
}

int gcd(int a, int b, int c) {
    int min = a;
    if (b < min) {
        min = b;
    }
    if (c < min) {
        min = c;
    }
    for (int i = min; i >= 1; i--) {
        if (a % i == 0 && b % i == 0 && c % i == 0) {
            return i;
        }
    }
    return 1;
}