2954: 大整数乘法（C++）借助vector计算

#include<iostream>
#include<vector>
#include<algorithm> 
using namespace std;
//success
vector<int> mul(vector<int> &A , vector<int> &B)
{
    vector<int> C(A.size() + B.size() , 0);
    for(int i = A.size() - 1;i >= 0;i --)
    {
        for(int j = B.size() - 1;j >= 0;j --)
        {
            int t = A[i] * B[j];
            int sum = C[i + j + 1] + t;
            C[i + j] += sum / 10; // 进位
            C[i + j + 1] = sum % 10;
        }
    }
    reverse(C.begin() , C.end()); //将结果改为倒序
    while(C.size() > 1 && C.back() == 0) C.pop_back(); //去除前导零
    return C;
}
int main()
{
    string a , b;
    cin>>a>>b;
    vector<int> A , B;
    for(int i = 0;i < a.size() ;i++) A.push_back(a[i] - '0'); //顺序存储 
    for(int i = 0;i < b.size() ;i++) B.push_back(b[i] - '0');
    vector<int> D = mul(A , B);
    for(int i = D.size() - 1;i >= 0; i--) printf("%d" , D[i]);
    return 0;
}