NPTEL(WEEK-4.4)

Programming Assignment 4.4 : Triplet Search

Given an array of unique numbers and a value, a valid triplet is a set of three numbers (not necessarily continuous in the array) that add up to the value. Write a program to count all valid triplets. Print the number of  valid triplets. Hint: Can you solve this in O(n^2) steps?

Input : First line contains N and Sum (Space separated). Second line contains space separated list of N numbers.

Output: Number of triplets such that  sum possible

Constraints:

• 0 < N < 100
• All numbers in the list are unique and between -10^4 to 10^4
• -10^3 < Sum < 10^
  3

# include <stdio.h>

int find3Numbers(int A[], int arr_size, int sum)

{

    int l, r,c=0,i,j,k;

    for (i = 0; i < arr_size-2; i++)

    {

       for (j = i+1; j < arr_size-1; j++)

       {

            for (k = j+1; k < arr_size; k++)

           {

               if (A[i] + A[j] + A[k] == sum)

               {

                 c++;

               }

           }

       }

    }

   return c;

}

int main()

{

    int A[100];

    int sum;

  int ans;

    int size,i;

  scanf("%d%d",&size,&sum);

  for(i=0;i<size;i++)

    scanf("%d",&A[i]);

    ans=find3Numbers(A, size, sum);

  printf("%d",ans);

    return 0;

}