PAT甲级 1001 A+B Format (20 分)

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字符串操作

#include<bits/stdc++.h>
#define FI first
#define SE second

using namespace std;
const int maxn = 1000 + 7;
typedef long long ll;

typedef pair<int,int> P;

int a, b;

int main() {
    cin >> a >> b;
    a += b;
    if(a < 0) {
        cout << '-';
        a *= (-1);
    }
    int t = 0;
    string s;
    while(1) {
        s.push_back((char)(a%10+'0'));
        a /= 10;
        t++;
        if(!a) break;
        if(t == 3) {
            s.push_back(',');
            t = 0;
        }
    }
    reverse(s.begin(), s.end());
    cout << s;

    return 0;
}