题解 | #高精度整数加法#

#include <algorithm>
#include <iostream>
#include <iterator>
#include <string>
#include <vector>
using namespace std;

int main() {
    string str1, str2;
    cin >> str1 >> str2;
    int maxLen = max(str1.length(), str2.length());
    int minLen = min(str1.length(), str2.length());
    string addition;//补零的位数
    for(int i = 0; i < maxLen - minLen; i++){
        addition += '0';
    }
    if(str1.length() > str2.length()) str2 = addition + str2;//往位数小的数高位补零
    else if(str2.length() > str1.length()) str1 = addition + str1;
    vector<int> vec;
    int carry = 0;//每次运算的进位
    for(int i = maxLen - 1; i >= 0; i--){
        int sum = str1[i] - '0' + str2[i] - '0' + carry;
        vec.push_back(sum % 10);
        carry = sum / 10;
    }
    if(carry != 0) vec.push_back(carry);//最高位可能也有进位
    reverse(vec.begin(), vec.end());
    for(int it : vec) cout << it;
    return 0;
}