fork(1) download
copy 
  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. int main(){
  4.   ios_base::sync_with_stdio(false);
  5.   cin.tie(NULL);
  6.   int t;
  7.   cin >> t;
  8.   while(t--){
  9.     int n = 0;
  10.     cin >> n;
  11.  
  12.     int par = 0, impar = 0;
  13.     for(int i=0; i < n; i++){
  14.       int num ; 
  15.       cin >> num;
  16.       if(i % 2 == 0){
  17.         if(num % 2 != 0){
  18.           impar++;
  19.         }
  20.       }else{
  21.         if(num % 2 == 0){
  22.           par++;
  23.         }
  24.       }
  25.     }
  26.     if(par != impar){
  27.       cout << -1 << "\n";
  28.     }else{
  29.       cout << par << "\n";
  30.     }
  31.   }
  32. }
Success #stdin #stdout 0s 5320KB
comments (?)
stdin
copy 
4
4
3 2 7 6
3
3 2 6
1
7
7
4 9 2 1 18 3 0
stdout
copy 
2
1
-1
0
https://ideone.com/VglKws
language:
C++ (gcc 8.3)
created:
7 days ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!