Neliöt

#include <iostream>
#include <string>
#include <map>

typedef long long ll;
using namespace std;

ll arr[31622];
map<int, int> m;

int main() {
  int t; cin>>t;
  for (int i = 1; (ll)i*i < 1e9; i++) {
    arr[i-1] = i*i;
    m[i*i] = 1;
  }

  for (int i = 0; i < t; i++) {
    int x; cin>>x;
    if (m[x]) {
      cout << "YES" << "\n";
      continue;
    }

    int a = 0, b = 31621;
    while (true) {
      if (a > b) {
        cout << "NO" << "\n";
        break;
      } else if (arr[a]+arr[b]==x) {
        cout << "YES" << "\n";
        break;
      }

      if (arr[a]+arr[b] < x) {
        a++;
      } else {
        b--;
      }
    }
  }
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 1, 2

Verdict: ACCEPTED

Test 3

Group: 2

Verdict: ACCEPTED