Two Sum Solution #1 - Brute Force Approach

TwoSumBruteForce.java

/**
*

Two Sum Solution #1 - Brute Force Approach
  
  Approach
    - Brute force approach by using a nested loop
    - Create the two loops to process the array, wherein the second loop is one step ahead of the previous loop and traversing the array elements in a quadratic manner
    - The first loop uses the variable i to hold the first index while the second loop uses the variable j to hold the latter one.
    - Compare the values of the i and j indices. If they are the same, return the indices as output
    - Return an empty integer array if no match was found

Complexity
    - Time complexity: O(n^2)
    - Space complexity: O(1)

*/

class TwoSumBruteForce {

    public int[] twoSum(int[] nums, int target) {

        for (int i=0; i < nums.length ;i++){

            for (int j=i+1; j < nums.length ;j++){
                if ((nums[i] + nums[j]) == target){
                   return new int[]{i,j};
                }
            }
        }

        // returns an empty array if no match found
        return new int[]{};
    }
}

Revision:

/**
*
Two Sum Solution #1 - Brute Force Approach
  
  Approach
    - Brute force approach by using a nested loop
    - Create the two loops to process the array, wherein the second loop is one step ahead of the previous loop and traversing the array elements in a quadratic manner
    - The first loop uses the variable i to hold the first index while the second loop uses the variable j to hold the latter one.
    - Compare the values of the i and j indices. If they are the same, return the indices as output
    - Return an empty integer array if no match was found
    
Complexity
    - Time complexity: O(n^2) where n is the number of input.
    - Space complexity: O(1)
*/

import java.util.Arrays;

class Main {
    
    public static void main(String args[]){
        int nums[] = {3,4,8,11,5};
        int target = 10;
        int indices[] = twoSum(nums,target);

        if (indices.length > 0){
            System.out.println("Result: " + Arrays.toString(indices));
            System.out.println("The sum of : " + nums[0] + " + " +nums[1] + " is " + target );
        } else{
            System.out.println("No match found."); 
        }
    }

    public static int[] twoSum(int[] nums, int target) {
        int ctr = 0;
        for (int i=0; i < nums.length ;i++){
            
            for (int j=i+1; j < nums.length ;j++){
                
                // Don't allow the same number
                if (nums[i] == nums[j]){
                    continue;
                }
                
                System.out.println(nums[i] + " "+ nums[j]);
                if ((nums[i] + nums[j]) == target){
                   System.out.println("Total number of steps: " + ctr);
                   return new int[]{i,j};
                }
                ctr++;
            }
            System.out.println();
           
        }
        System.out.println("Total number of steps: " + ctr);
        // returns an empty array if no match found
        return new int[]{};
    }
}