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Java Array Exercises: Find all the unique triplets such that sum of all the three elements equal to a specified number

Java Array: Exercise-36 with Solution

Write a Java program to find all the unique triplets such that sum of all the three elements [x, y, z (x ≤ y ≤ z)] equal to a specified number.
Sample array: [1, -2, 0, 5, -1, -4]
Target value: 2.

Pictorial Presentation:

Java Array Exercises: Find all the unique triplets such that sum of all the three elements equal to a specified number

Sample Solution:

Java Code:

import java.util.ArrayList;
import java.util.List;
public class Exercise36 {
    public static void main(String[] args) {
        int[] input = {1, -2, 0, 5, -1, -4};
		int target = 2;
		Exercise36 r = new Exercise36();
        System.out.println(r.threeSum(input,target));       
    }
    public List<List<Integer>> threeSum(int[] nums, int target) {
        List<List<Integer>> my_List = new ArrayList<List<Integer>>();
        
        for(int i = 0; i < nums.length; i++){
            for(int j = i; j < nums.length ;j++){
                for(int k = j; k<nums.length;k++){
                    if ( i != j && j != k && i != k && (nums[i] + nums[j] + nums[k] == target)){
                        List<Integer> inner_List = new ArrayList<Integer>(3);
                        inner_List.add(nums[i]);
                        inner_List.add(nums[j]);
                        inner_List.add(nums[k]);
                        my_List.add(inner_List);
                    }
                }
            }
        }
       return my_List;
    }
  }

Sample Output:

                                                                              
[[1, 5, -4], [-2, 5, -1]] 

Flowchart:

Flowchart: Java exercises: Find all the unique triplets such that sum of all the three elements equal to a specified number

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Previous: Write a Java program to find the sum of the two elements of a given array which is equal to a given integer.
Next: Write a Java program to create an array of its anti-diagonals from a given square matrix.

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Java: Tips of the Day

Different between parseInt() and valueOf() in java?

Well, the API for Integer.valueOf(String) does indeed say that the String is interpreted exactly as if it were given to Integer.parseInt(String). However, valueOf(String) returns a new Integer() object whereas parseInt(String) returns a primitive int.

If you want to enjoy the potential caching benefits of Integer.valueOf(int), you could also use this eyesore:

Integer k = Integer.valueOf(Integer.parseInt("123"))

Now, if what you want is the object and not the primitive, then using valueOf(String) may be more attractive than making a new object out of parseInt(String) because the former is consistently present across Integer, Long, Double, etc.

Ref: https://bit.ly/3vRuIPY