HackerEarth Sherlock and XOR problem solution

In this HackerEarth Sherlock and XOR problem solution, You are given an array A1, A2...AN. You have to tell how many pairs (i, j) exist such that 1 ≤ i < j ≤ N and Ai XOR Aj is odd.

HackerEarth Sherlock and XOR problem solution.

#include <cstdlib>
#include <stdio.h>
#include <cstring>
#include <complex>
#include <vector>
#include <cmath>
#include <ctime>
#include <iostream>
#include <numeric>
#include <algorithm>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <iomanip>
#include <utility>
#include <locale>
#include <sstream>
#include <string>
#include <istream>
#include <ostream>
#include<assert.h>

using namespace std;

#define FOR(i,n) for(i=0;i<n;i++)
#define FORI(i,a,n) for(i=a;i<n;i++)
#define FORC(it,C) for(it=C.begin();it!=C.end();it++)
#define scanI(x) scanf("%d",&x)
#define scanD(x) scanf("%lf",&x)
#define print(x) printf("%d\n",x)
#define ll  long long
#define number32 4294967296ull
#define MAX 100001
#define len(s) s.length()
#define ff first
#define ss second
#define IN(A, B, C)  (B) <= (A) && (A) <= (C)
#define AIN(A, B, C) assert(IN(A, B, C))
using namespace std;

typedef map<int,int> Mii;
typedef map<char,int> Mci;
typedef pair<int,int> Pii;
typedef vector<int> vi;
typedef vector<int> vc;
typedef vector<ll> vl;

typedef map<int,int>::iterator Miii;
typedef map<char,int>::iterator Mcii;

ll A[MAX+1];
int main()
{
    int t,i;
    int n;
    cin>>t;
    AIN(t,1,10);
    ll ceven,codd;
    ll ans;
    while(t--)
    {
        ceven=0;
        codd=0;
        cin>>n;
        AIN(n,1,100000);
        FOR(i,n)
        {
            cin>>A[i];
            AIN(A[i],0,1000000000);
            if(A[i]%2==0)
            {
                ceven++;
            }
            else codd++;
            
        }
        ans=ceven*codd;
        cout<<ans<<endl;
    }
    return 0;
}