192A - Funky Numbers - CodeForces Solution

#include<cstring>
#include <bits/stdc++.h>
#define all(a) a.begin(), a.end()
#define allr(a) a.rbegin(), a.rend()
#include <iostream>
#include <cmath>
#include <stdio.h>
#include <algorithm>
#include <iostream>
#include <cstring>
typedef long long ll;
typedef unsigned long long ull;
using namespace std;
const ull N = (1e7)/2+10;
const ll INF =1e18;
const ull M= 998244353;

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    ll t = 1;
//    cin >> t;
    while(t--){
         ll n;
         cin >> n;
         set<ll>s;
         vector<ll>v;
         for(int i = 1 ; i < 1e5 ; i++){
            ll bng  = (1LL*i*(i+1)/2);
            s.insert(bng);
            v.push_back(bng);
         }
         ll f = 0 ;
         for(int i = 0 ; i < v.size()  ;i++){
            if(s.find(n-v[i]) != s.end() && n-v[i] > 0){
                f=1;
                break;
            }
         }
         if(f) cout << "YES" <<endl;
         else cout << "NO" <<endl;


    }














    return 0;
}