1669C - Odd-Even Increments - CodeForces Solution

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

int main()
{
    int tc;
    cin >> tc;
    int n,even,odd;
    bool ans;

    while(tc--){
        cin >> n;
        int a[n];
        for(int i=0; i<n; i++){
            cin >> a[i];
        }
        even=odd=0;
        ans = true;

        for(int i=0; i<n; i+=2){
            if(a[i]%2==0) even++;
            else odd++;
            if(even>0 and odd>0) ans = false;
        }
        even=odd=0;
        for(int i=1; i<n; i+=2){
            if(a[i]%2==0) even++;
            else odd++;
            if(even>0 and odd>0) ans = false;
        }

        if(ans) cout << "YES\n";
        else cout << "NO\n";
    }

}