c - Rotating array (Larray hackerrank) -

i not able logic behind solution problem . thankful if can explain me working of it.

solution:

#include <bits/stdc++.h> using namespace std; const int n=1509; int n; int a[n];  void input(){     scanf("%d",&n);     (int i=1;i<=n;i++)         scanf("%d",&a[i]); }  void sol(){     int k=1;     (int i=1;i<=n;i++)     (int j=i+1;j<=n;j++)         k^=(a[i]>a[j]);     if (k) printf("yes\n");     else printf("no\n"); }  int main() {     int test;     scanf("%d",&test);     while (test--){         input();         sol();         }     return 0; } 

i not able how after xoring each permutation, value of 'k' in end determining answer(ie whether can arranged in sorting order) ?

when rotate block change number of inversions +/- 2 or 0 (work out on paper, if don't trust me). if number of inversions in array odd not able make sorted given operation. you'll end array sorted 2 elements in place (1 inversion) , can't fix given operation.

what code check if number of inversions odd xoring every time sees inversion. can same result if count inversions , check inversions % 2 == 0.