백준 5949 Adding Commas (USACO December 2010 Bronze 3번)

문제 링크: https://www.acmicpc.net/problem/5949

5949번: Adding Commas

#include <bits/stdc++.h>
using namespace std;
 
int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
 
    string s, ans;
    cin >> s;
    int sz = s.size();
    if(sz > 9) {
        s.insert(1, ",");
        s.insert(5, ",");
        s.insert(9, ",");
    }
    else if(sz > 6) {
        s.insert(sz - 6, ",");
        s.insert(sz - 2, ",");
    }
    else if(sz > 3) {
        s.insert(sz - 3, ",");
    }
 
    cout << s;
    return 0;
}
 

#include <bits/stdc++.h>
using namespace std;
 
int main() {
    string s;
    cin >> s;
    int n = s.size();
 
    for(int i = 0; i < n; i++) {
        if(i > 0 && (n - i) % 3 == 0) cout << ',';
        cout << s[i];
    }
    cout << '\n';
    
    return 0;
}