202C - Clear Symmetry - CodeForces Solution

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

#define FAST ios_base::sync_with_stdio(false); cin.tie(NULL);

int main() {

    vector<int> arr(101, 0);
    arr[1] = 1;
    arr[2] = 3;
    arr[3] = 5;
    arr[4] = 3;
    arr[5] = 3;


    for(int i = 5;i<=100;i+=2)
    {
        int y = i/2;
        int z = y+1;
        int r = z*z + y*y;

        for(int j = 1;j<=100;j++)
        {
            if(j <= r && !arr[j]) arr[j] = i;
        }
    }
    int x;
    cin>>x;
    cout<<arr[x];
}