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Two Sum

Certification: Basic Level Accuracy: 32.94% Submissions: 419 Points: 5

Write a Java program to implement the twoSum(int[] nums, int target) function, which finds indices of two numbers in an array such that they add up to a specific target. You may assume that each input would have exactly one solution, and you may not use the same element twice.

Example 1
    

  • Input: nums = [2, 7, 11, 15], target = 9
    • 

  • Output: [0, 1]
    • 

  • Explanation:

      

    • nums[0] = 2 → looking for 7
      • 

    • nums[1] = 7 → found complement
      • 

    • Return [0, 1] since 2 + 7 = 9
      • 

    

    •
Example 2
    

  • Input: nums = [3, 2, 4], target = 6
    • 

  • Output: [1, 2]
    • 

  • Explanation:

      

    • nums[1] = 2 → looking for 4
      • 

    • nums[2] = 4 → found complement
      • 

    • Return [1, 2] since 2 + 4 = 6
      • 

    

    •
Constraints
    

  • 2 ≤ nums.length ≤ 10^4
    • 

  • -10^9 ≤ nums[i] ≤ 10^9
    • 

  • -10^9 ≤ target ≤ 10^9
    • 

  • Time Complexity: O(n)
    • 

  • Space Complexity: O(n)
    •
ArraysNumberIBMDeloitte
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Hint
Solution

Solution Hints

    
  
  • Use a HashMap to store values and their indices as you iterate through the array
    • 
  
  • For each element, check if its complement (target - current element) exists in the HashMap
    • 
  
  • If found, return the indices of the current element and its complement
    • 
  
  • Otherwise, add the current element and its index to the HashMap
    •

Steps to solve by this approach:

 Step 1: Create a HashMap to store array elements and their indices.
 Step 2: Iterate through the array one element at a time.
 Step 3: For each element, calculate its complement (target - current element).
 Step 4: Check if the complement exists in the HashMap.
 Step 5: If found, return the indices of both numbers.
 Step 6: If not found, add the current element and its index to the HashMap.
 Step 7: Continue until a solution is found or the array is exhausted.

Submitted Code :