题解 | a+b

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

int chartonum(char a) {
    return a - '0';
}

int bigger(int a, int b) {
    if (a > b)return a;
    else return b;
}

void reverse(char str[]) {
    int len = strlen(str);
    int i = 0;
    while (i < len) {
        char temp = str[i];
        str[i] = str[len - 1];
        str[len - 1] = temp;
        i++;
        len--;
    }
}
int main() {
    string str1, str2;
    while (cin >> str1 >> str2) {
        int len1 = str1.length();
        int len2 = str2.length();


        char str[bigger(len1, len2) + 2];
        int i = len1 - 1, j = len2 - 1, k = 0, m = 0;
        while (i >= 0 && j >= 0) {
            int t = (chartonum(str1[i]) + chartonum(str2[j]) + m) / 10;
            str[k++] = (chartonum(str1[i]) + chartonum(str2[j]) + m) % 10 + '0';
            m = t;
            i--;
            j--;
        }
        while (i >= 0) {
            int t = (chartonum(str1[i]) + m) / 10;
            str[k++] = (chartonum(str1[i]) + m) % 10 + '0';
            m = t;
            i--;
        }
        while (j >= 0) {
            int t = (chartonum(str2[j]) + m) / 10;
            str[k++] = (chartonum(str2[j]) + m) % 10 + '0';
            m = t;
            j--;
        }
        if (m != 0) {
            str[k++] = m + '0';
        }
        str[k] = '\0';
        reverse(str);
        for(int i = 0;i<strlen(str);i++)
        {
            cout<<str[i];
        }
        cout<<endl;

    }
    return 0;
}