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Java Array Exercises: Find all combination of four elements of a given array whose sum is equal to a given value

Java Array: Exercise-43 with Solution

Write a Java program to find all combination of four elements of a given array whose sum is equal to a given value.

Pictorial Presentation:

Java Array Exercises: Find all combination of four elements of an given array whose sum is equal to a given value

Sample Solution:

Java Code:

import java.util.*;
import java.lang.*;
public class Main
{
   public static void main (String[] args) 
    {  
      int nums[] = {10, 20, 30, 40, 1, 2};
      int n = nums.length;
      // given value
      int s = 53;
       System.out.println("Given value: "+s);
        System.out.print("Combination of four elements:");  
        // Find other three elements after fixing first element
        for (int i = 0; i < n - 3; i++) 
        {
          // Find other two elements after fixing second element
            for (int j = i + 1; j < n - 2; j++) 
            {
           // Find the fourth element after fixing third element    
              for (int k = j + 1; k < n - 1; k++) 
                {
            // find the fourth
                    for (int l = k + 1; l < n; l++) 
                    {
                        if (nums[i] + nums[j] + nums[k] + nums[l] == s) 
                            System.out.print("\n"+nums[i]+" "+nums[j]+" "+nums[k] 
                                                                 +" "+nums[l]);
                    }
                }
            }
    }
  }
}

Sample Output:

                                                                              
Given value: 53
Combination of four elements:
10 40 1 2
20 30 1 2

Flowchart:

Flowchart: Find all combination of four elements of an given array whose sum is equal to a given value

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Java Code Editor:

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Previous: Write a Java program to segregate all 0s on left side and all 1s on right side of a given array of 0s and 1s.
Next: Write a Java program to count the number of possible triangles from a given unsorted array of positive integers.

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Java: Tips of the Day

Array vs ArrayLists:

The main difference between these two is that an Array is of fixed size so once you have created an Array you cannot change it but the ArrayList is not of fixed size. You can create instances of ArrayLists without specifying its size. So if you create such instances of an ArrayList without specifying its size Java will create an instance of an ArrayList of default size.

Once an ArrayList is full it re-sizes itself. In fact, an ArrayList is internally supported by an array. So when an ArrayList is resized it will slow down its performance a bit as the contents of the old Array must be copied to a new Array.

At the same time, it's compulsory to specify the size of an Array directly or indirectly while creating it. And also Arrays can store both primitives and objects while ArrayLists only can store objects.

Ref: https://bit.ly/3o8L2KH