Median Program In C


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A median value is the value at the center of a sorted list. To median we need to sort the list in ascending or descending order.

For Example take the list of 3, 5, 2, 7, 3 as our input list. To find out median, first we re-order it as 2, 3, 3, 5, 7. and we find that at location 3 ((5+1)/2) is 3. So the value of median in this list is 3.

Algorithm

Algorithm of this program is very easy −

START
   Step 1 → Take an integer list A of n values
   Step 2 → Arrange the values in the list in some order, say ascending
   Step 3 → Calculate the middle of list → (n + 1) / 2
   Step 4 → Display the middle value as median
STOP

Pseudocode

We can derive pseudocode based on the algorithm, as −

procedure median()
   
   Array A
   Size  N
   SORT(A)
   middle = (N + 1) / 2
   DISPLAY A[middle] as median

end procedure

Implementation

Implementation of this algorithm is given below −

#include <stdio.h>

void swap(int *p,int *q) {
   int t;
   
   t=*p; 
   *p=*q; 
   *q=t;
}

void sort(int a[],int n) { 
   int i,j,temp;

   for(i = 0;i < n-1;i++) {
      for(j = 0;j < n-i-1;j++) {
         if(a[j] > a[j+1])
            swap(&a[j],&a[j+1]);
      }
   }
}

int main() {
   int a[] = {6,3,8,5,1};
   int n = 5;
   int sum,i;

   sort(a,n);
   
   n = (n+1) / 2 - 1;      // -1 as array indexing in C starts from 0

   printf("Median = %d ", a[n]);

   return 0;
}

Output

Output of the program should be −

Median = 5 
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