代码如下

#include <bits/stdc++.h>

using namespace std;

const int maxn = 2005;
char s1[maxn],s2[maxn];
int a[maxn],b[maxn],c[maxn];

int main()
{
    scanf("%s%s",s1,s2);
    int la = strlen(s1);
    int lb = strlen(s2);

    for(int i = 0;i < la;i++)
        a[la - i - 1] = s1[i] - '0';
    for(int i = 0;i < lb;i++)
        b[lb - i - 1] = s2[i] - '0';

    int lc = la + lb;
    memset(c,0,sizeof(c));

    for(int i = 0;i < la;i++)
    {
        for(int j = 0;j < la;j++)
        {
            c[i + j] += a[i] * b[j];
        }
    }
    for(int i = 0;i <= lc;i++)
    {
        if(c[i] >= 10)
        {
            c[i + 1] += c[i] / 10;
            c[i] %= 10;
        }
    }

    while(c[lc] == 0 && lc > 0)
        lc--;

    for(int i = lc;i >= 0;i--)
        printf("%d",c[i]);
        printf("\n");
    return 0;
}

求助！！！