Problem

http://e-tutor.itsa.org.tw/e-Tutor/mod/programming/view.php?id=2969

Thinking

TODO

Solution

#include <iostream>
#include <set>

using namespace std;

int main(){
    int num;
    while(cin >> num){
        set<int> S;
        S.insert(1);
        for(int T = 2 ; S.size() != num ;T++ ){
            set<int>::iterator search = S.find(T);
            if(search == S.end()){
                S.insert(*S.rbegin() + T);
            }
        }
        cout << *S.rbegin() << endl;
    }
}