萌新在此，求大佬帮忙优化

#include<bits/stdc++.h>
using namespace std;
int main(){
    int k;
    cin >> k;
    int coin = 0;
    int zts = 0, flag = 0;
    for(int shouru = 1;flag == 0;shouru++){
        for(int day = 1; day <= shouru; ++day){
            coin += shouru;
            ++zts;
            if(zts == k){
                flag = 1;
                break;
            }
        }
    }
    cout << coin;
    return 0;
}