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  1. #include <stdio.h>
  2. int s[100000],ct,sum;
  3. void count(int val);
  4. void mergesort(int a[],int l,int h);
  5. int main(void) {
  6. 	// your code goes here
  7. 	int n,i;
  8. 	scanf("%d",&n);
  9. 	int a[n];
  10. 	for(i=0;i<n;i++)
  11. 	scanf("%d",a+i);
  12. 	mergesort(a,0,n-1);
  13. 	printf("%d",sum);
  14. 	return 0;
  15. }
  16. void mergesort(int a[],int l,int h)               // O(nlogn)
  17. {
  18.     if(l<h)
  19.     {
  20.         int mid=l+(h-l)/2;
  21.         mergesort(a,l,mid);                                       
  22.         mergesort(a,mid+1,h);
  23.     }
  24.     else if(l==h)
  25.     {
  26.         count(a[l]);                               
  27.     }
  28. }
  29. void count(int val)                                   //O(n)
  30. {
  31.     int i;
  32.     if(ct==0)
  33.     {
  34.     s[0]=val;
  35.     ct++;
  36.     }
  37.     else
  38.     {
  39.         for(i=0;i<ct;i++)
  40.         {
  41.             if(s[i]>val)
  42.             {
  43.             sum+=1;
  44.          //   printf("pair = %d %d\n",s[i],val);
  45.             }
  46.         }
  47.         s[i]=val;
  48.         ct+=1;
  49.     }
  50. }
  51.  
Success #stdin #stdout 0.03s 4544KB
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https://ideone.com/7p81JM
language:
C (gcc 8.3)
created:
4 years ago
visibility:
public

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