#include <stdio.h>
#include <string.h>
#define MAX_LEN 1000
// 计算两个大整数的乘积
void multiply(const char* a, const char* b, char* result) {
    int lenA = strlen(a), lenB = strlen(b), lenResult = lenA + lenB;
    int arr[MAX_LEN * 2] = {0};

    // 进行乘法运算
    for (int i = 0; i < lenA; ++i)
        for (int j = 0; j < lenB; ++j)
            arr[i + j] += (a[lenA - i - 1] - '0') * (b[lenB - j - 1] - '0');
    // 处理进位
    for (int i = 0; i < lenResult - 1; ++i) {
        arr[i + 1] += arr[i] / 10;
        arr[i] %= 10;
    }    
    // 构建结果字符串
    int index = 0;
    while (index < lenResult && arr[index] == 0) ++index;
    if (index == lenResult) strcpy(result, "0");
    else {
        for (int i = index; i < lenResult; ++i)
            result[i - index] = arr[lenResult - i - 1] + '0';
        result[lenResult - index] = '\0';
    }
}

int main() {
    char a[MAX_LEN + 1], b[MAX_LEN + 1], result[MAX_LEN * 2 + 1];
    printf("输入第一个大整数: ");
    scanf("%s", a);
    printf("输入第二个大整数: ");
    scanf("%s", b);
    multiply(a, b, result);
    printf("结果: %s\n", result);
    return 0;
}
