题目描述

模板题：高精度减法

C++代码

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

vector<int> sub(vector<int> &A, vector<int> &B){
    vector<int> C;
    int t = 0;
    for(int i = 0; i < A.size(); i++){
        if(i < B.size())
            t = A[i] - B[i] - t;
        else
            t = A[i] - t;
        C.push_back((t + 10) % 10);
        if(t < 0)
            t = 1;
        else
            t = 0;
    }
    while(C.size() > 1 && C.back() == 0) //减法可能造成全零，得去掉多余的0
        C.pop_back();
    return C;
}

bool cmp(vector<int> &A, vector<int> &B){
    if(A.size() != B.size())
        return A.size() > B.size();
    else{
        for(int i = A.size() - 1; i >= 0; i--)
            if(A[i] != B[i])
                return A[i] > B[i];
    }
    return true;
}

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