poj 1001 Exponentiation

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

int n, p, len, flag;
char a[10],s[10], sum[200], sum2[200];

void solve()
{
    memset(sum2,0,sizeof(sum2));
    len += 5;
    for(int i = 0; i < p; i ++)
    {
        int c = 0;
        for(int j = 0; j <= len; j ++)
        {
            sum2[i+j] += s[i]*sum[j] + c;
            c = sum2[i+j]/10;
            sum2[i+j] = sum2[i+j]%10;
        }
    }
    for(int i = 0; i <= len+5; i ++)
        sum[i] = sum2[i];
    //for(int i = 0; i <= len+5; i ++)
    //    printf("%d ",sum[i]);
    //puts("");
    //getchar();getchar();
}

int main()
{
    while(~scanf("%s%d",&a, &n))
    {
        memset(sum, 0, sizeof(sum));
        p = 0;
        for(int i = 5; i >= 0; i --)
            if(a[i] != '.') 
            {
                sum[p] = a[i]-'0';
                s[p++] = a[i]-'0';
            }
            else flag = i;
        len = 0;
        for(int i = 0; i < n-1; i ++)
            solve();
        int i, j;
        for(i = n*5; i >=0; i --)
            if(sum[i] != 0 || i == n*(5-flag)) break;
        
        for(j = 0; j <= n*5; j ++)
            if(sum[j] != 0 || j == n*(5-flag) )break;//printf("i=%d j=%d\n",i,j);
        //printf("sum[49]=%d\n",sum[49]);
        for(int k = i; k >= j; k --)
        {
            if(k == i && i == n*(5-flag))
            {
                if(sum[k] != 0) printf("%d",sum[k]);
                if(n*(5-flag) != j)printf(".");
            }
            else
            {
                printf("%d",sum[k]);
                if(k == j && j == n*(5-flag));
                else if(k == n*(5-flag)) printf(".");
            }    
        }
        puts("");
    }
    return 0;
}