Bitwise Blend.cpp

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

long long be1[200002];
long long be2[200002];
long long Be1=0;
long long Be2=0;
//first function
void function1(long long x,long long y){
    be1[Be1]=x;
    Be1++;
    be1[Be1]=y;
    Be1++;
}
//second function
void function2(long long x,long long y){
    be2[Be2]=x;
    Be2++;
    be2[Be2]=y;
    Be2++;
}
//main function
int main()
{
    long long t;
    cin >> t;
    while(t--){
        Be1=0;
        Be2=0;
        
        long long count_1 = 0;
        long long count_2 = 0;
        
        long long n;
        cin >> n;
        long long a[n];
        long long A[n];
        
        long long Y1=0,Y=2;
        long long y1=0,y=0;
        
        long long odd_check =0;
        for(long long i=0; i<n ;i++){
            cin>>a[i];
            A[i]=a[i];
        }
       
if(a[0]%2==0)
{
    if(a[1]%2==0){
         
         for(long long i=2;i<n;i++){
             if(a[i]%2==1){
                 Y1=a[i];
                 y1=i;
                 odd_check = 1;
                 
                 a[1] = a[1]^Y1;
                 count_1++;
                 function1(1,y1);
                 break;
             }
         }
         
    }
    else{
        Y1=a[1];
        y1=1;
        odd_check = 1;
    }
      Y=a[1];
      y=1;
      for(long long i =2;i<n;i++){
          if(a[i]%2==1){
              a[i]=a[i]^Y;
              count_1++;
              function1(i,y);
          }
          i++;
          if(i<n){
              if(a[i]%2==0){
                  a[i]=a[i]^Y;
              count_1++;
              function1(i,y);
              }
          }
      }
      A[0]=A[0]^Y1;
      count_2++;
      function2(0,y1);
      
      Y=A[0];
      y=0;
      
      for(long long i=1;i<n;i++){
          if(A[i]%2==1){
              A[i]=A[i]^Y;
              count_2++;
              function2(i,y);
          }
          i++;
          if(i<n){
              if(A[i]%2==0){
                  A[i]=A[i]^Y;
                  count_2++;
                  function2(i,y);
              }
          }
      }
  
    
}
else{
    odd_check = 1;
    Y=A[0];
    y=0;
    for(long long i=1;i<n;i++){
        if(a[i]%2==1){
            a[i]=a[i]^Y;
            count_1++;
            function1(i,y);
        }
        i++;
        if(a[i]%2==0 && i<n){
            a[i]=a[i]^Y;
            count_1++;
            function1(i,y);
        }
    }
    
    Y = A[0];
    y=0;
    
    for(long long i=1;i<n;i++){
        if(A[i]%2==0){
            A[i]=A[i]^Y;
            count_2++;
            function2(i,y);
        }
        i++;
        if(A[i]%2==1 && i<n){
            A[i]=A[i]^Y;
            count_2++;
            function2(i,y);
        }
    }
    
    A[0]=A[0]^A[1];
    count_2++;
    function2(0,1);

}
 if(odd_check==0){
     cout<<"-1"<<endl;
 }
 else if(count_1>count_2){
     long long j;
     cout<<count_2<<endl;
     for(long long i=0;i<count_2;i++){
         j=i*2;
         cout<<be2[j]+1<<" "<<be2[j+1]+1<<endl;
     }
 }
 else{
     int j;
     cout<<count_1<<endl;
     for(long long i=0;i<count_1;i++){
         j=i*2;
         cout<<be1[j]+1<<" "<<be1[j+1]+1<<endl;
     } }

    }
        
      return 0;  
}