题目描述

模板题：高精度乘法

C++代码

#include <bits/stdc++.h>
#include <vector>
using namespace std;

vector<int> mul(vector<int> &A, int b){
    vector<int> C;
    int t = 0;
    for(int i = 0; i < A.size(); i++){
        t += A[i] * b;
        C.push_back(t % 10);
        t /= 10;
    }
    if(t) //可能还有残留进位
        C.push_back(t);
    while(C.size() > 1 && C.back() == 0) //乘0时候，所有位置为0
        C.pop_back();
    return C;
}

int main(){
    string a;
    int b;
    vector<int> A, C;
    cin >> a >> b;
    for(int i = a.size() - 1; i >= 0; i--)
        A.push_back(a[i] - '0');
    C = mul(A, b);
    for(int i = C.size() - 1; i >= 0; i--)
        cout << C[i];
    cout << endl;
}