POJ问题集

1001：

#include<stdio.h>
#include<string.h>
#include<malloc.h>

void multiple(char *a,char* b,char* m)
{
    int c[150] = {0};
    int l1 = strlen(a),l2 = strlen(b),len;
    for(int i=0;i<l1+l2-1;i++)
    {
        for(int j=0;j<=l1+l2-2-i;j++)
        {
            if(j < l1 && l1 < 2+i+j)
            {
                c[i] += (a[j]-'0')*(b[l1+l2-2-i-j]-'0');
            }
        }
    }
    for(int i=0;i<l1+l2+1;i++)
    {
        c[i+1]+=c[i]/10;
        c[i] = c[i]%10;
    }
    for(len = l1+l2;len > 0;len--)// len equals to the length of result -1;
    {
        if( c[len] != 0)
            break;
    }
    for(int i=0;i<=len;i++)
        m[i] = c[len-i] + '0';
}

void power(char *a,int n,char *p)
{
    strcpy(p,a);
    for(int i=1;i<n;i++)
        multiple(a,p,p);
}

int trans(char *a) //return the number of digit after dot and clear 0 at tail
{
    int n = 0,l = strlen(a),m=l-1;
    for(int i=0;i<l;i++)
    {
        if(a[i] == '.')
        {
            while(a[m] == '0')
            {
                a[m] = '\0';
                m--;
            }
            n = strlen(a)-i-1;
            a[i] = '\0';
            strcat(a,a+i+1);

            break;
        }
    }
    return n;
}

void addDot(char *a,int n) //add dot at n_th place(count backwards)
{
    if(n == 0) return;
    int l = strlen(a);
    if(l>n)
    {
        for(int i=0;i<n;i++)
        {
            a[l-i] = a[l-i-1];
        }
        a[l-n] = '.';
    }
    else
    {
        char b[150] = {0};
        b[0] = '.';
        memset(b+1,'0',(n-l)*sizeof(char));
        strcat(b,a);
        strcpy(a,b);
    }
}

int main()
{
    char s[6];
    char res[150] = {0};
    int n;
    while(scanf("%s %d",s,&n) == 2)
    {
        memset(res,0,150 * sizeof(char));
        int k = trans(s);
        power(s,n,res);
        addDot(res,n*k);
        printf("%s\n",res);
    }
    return 0;
}