Array Inversion

• Problem Description

  
  Number of an inversion in array is the number of pair(a[i],a[j]) of elements such that i < j and a[i] > a[j]. For an example if we have a list of element 2 3 6 9 1 then number of inversion is 4 and the pairs are (2,1), (3,1), (6,1) and (9,1).
  Input:
  The first line is N, N is the size of array.
  The second line contains N input C[i].
  

• Test Case 1

  
  Input (stdin)

  5
  
  2 3 6 9 1
  
  

  Expected Output

  4

• Test Case 2

  
  Input (stdin)

  5
  
  1 2 3 5 6
  
  

  Expected Output

  0

• Program

• #include <stdio.h>
  int arrinv(int ar[], int a)
  {
    int i,j,c=0;
    for(i=0;i<a;i++)
    {
      for(j=i+1;j<a;j++)
      {
        if(ar[i]>ar[j])
          c++;
      }
    }
    return c;
  }
          
  int main()
  {
    int a,i;
    scanf("%d",&a);
    int arr[a];
    for(i=0;i<=a;i++)
    {
      scanf("%d",&arr[i]);
    }
    printf("%d",arrinv(arr,a));
  
   return 0;
  }