target_sum_triplets.java

import java.util.*;

class target_sum_triplets {
    
    public static void main(String args[]) {
        Scanner sc = new Scanner(System.in); // input
        int n = sc.nextInt(); //  array size

        int arr[] = new int[n];

        for (int i = 0; i < n; i++){
            arr[i] = sc.nextInt();// array elements
        }

        int target = sc.nextInt(); // target sum

        Arrays.sort(arr);

        for (int j = 0; j < n - 1; j++) {
            int start = j + 1;
            int end = n - 1;

            while (start < end) {

                if (arr[j] + arr[start] + arr[end] == target) {
                    System.out.println(arr[j] + ", " + arr[start] + " and " + arr[end]); // output 
                    start++;
                    end--;
                } else if (arr[j] + arr[start] + arr[end] < target)
                    start++;

                else
                    end--;
            }
        }
    }
}

/* Sample Input Output ->
Input
9
5 7 9 1 2 4 6 8 3
10

Output
1, 2 and 7
1, 3 and 6
1, 4 and 5
2, 3 and 5 

Complexity Analysis

Time Complexity - O(n^2)
Space Complexity - O(1) */