题解

#include <iostream>
#include <cstring>
using namespace std;
char a[2005], b[2005];
short a1[10005], b1[10005], c[10005];
int x;
int main(){
	cin >> a >> b;
	int lena = strlen(a), lenb = strlen(b);
	for(int i = 0; i < lena; i++){//倒序
		a1[lena - i] = a[i] - '0';
	}for(int i = 0; i < lenb; i++){
		b1[lenb - i] = b[i] - '0';
	}
	for(int i = 1; i <= lena; i++){//乘法
		int x = 0;
		for(int j = 1; j <= lenb; j++){
			c[i + j - 1] = x + a1[i] * b1[j] + c[i + j - 1];
			x = c[i + j - 1] / 10;
			c[i + j - 1] %= 10;
		}
		c[i + lenb] = x;
	}
	int maxn = lena + lenb;
	while(c[maxn] == 0 && maxn > 1) maxn--;
	for(int i = maxn; i > 0; i--) cout << c[i];
	
}