大数乘

#include <bits/stdc++.h>
using namespace std;
char s1[101], s2[101];
int s[205];
int main() {
	scanf("%s%s", s1, s2);
	int n = strlen(s1);
	int m = strlen(s2);
	if (n > m) {
		swap(s1, s2);
		swap(n, m);
	}
	reverse(s1, s1 + n);
	reverse(s2, s2 + m);
	for (int i = 0; i < n; i++) {
		int c = 0, x = 0, j = 0;
		for (; j < m; j++) {
			c += (s1[i]-'0') * (s2[j]-'0');
			x = (s[i + j] + c) / 10;
			s[i + j] = (s[i + j] + c) % 10;
			c = x;
		}
		while (c) {
			x = (s[i + j]+ c) / 10;
			s[i + j] = (s[i + j] + c) % 10;
			c = x;
			j++;
		}
	}
	int i = n + m;
	for (; i > 0; i--)if (s[i])break;
	for (; i >= 0; i--)printf(i == 0 ? "%d\n":"%d", s[i]);
	return 0;
}