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Target Sum

Certification: Intermediate Level Accuracy: 100% Submissions: 2 Points: 10

Write a Python program to find all unique pairs of numbers in an array that sum up to a given target value. Each pair should be returned as an array of two numbers, and the result should not contain duplicate pairs.

Example 1
    
  
  • Input: nums = [1, 2, 3, 4, 5, 6], target = 7
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  • Output: [[1, 6], [2, 5], [3, 4]]
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  • Explanation: 
    • We need to find pairs that sum to 7. 
    • 1 + 6 = 7, so [1, 6] is a valid pair. 
    • 2 + 5 = 7, so [2, 5] is a valid pair. 
    • 3 + 4 = 7, so [3, 4] is a valid pair. 
    • Therefore, we have three pairs that sum to 7.
    •
Example 2
    
  
  • Input: nums = [1, 1, 2, 2, 3, 3], target = 4
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  • Output: [[1, 3], [2, 2]]
    • 
  
  • Explanation: 
    • We need to find pairs that sum to 4. 
    • 1 + 3 = 4, so [1, 3] is a valid pair. 
    • 2 + 2 = 4, so [2, 2] is a valid pair. 
    • We avoid duplicate pairs, so only unique combinations are returned.
    •
Constraints
    
  
  • 2 ≤ nums.length ≤ 1000
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  • -10^9 ≤ nums[i] ≤ 10^9
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  • -10^9 ≤ target ≤ 10^9
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  • Return pairs in ascending order
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  • Each pair should be in ascending order [smaller, larger]
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  • Time Complexity: O(n log n)
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  • Space Complexity: O(n)
    •
ArraysWiproPwC
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Hint
Solution

Solution Hints

    
  
  • Sort the array first to make it easier to find pairs and avoid duplicates
    • 
  
  • Use two pointers approach - one at the beginning and one at the end
    • 
  
  • If the sum of elements at both pointers equals target, add to result
    • 
  
  • If sum is less than target, move left pointer right
    • 
  
  • If sum is greater than target, move right pointer left
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  • Skip duplicate elements to avoid duplicate pairs
    •

Steps to solve by this approach:

 Step 1: Sort the input array in ascending order to enable two-pointer technique.
 Step 2: Initialize left pointer at start (0) and right pointer at end (length-1).
 Step 3: Calculate sum of elements at left and right pointers.
 Step 4: If sum equals target, add pair to result and move both pointers.
 Step 5: If sum is less than target, move left pointer right to increase sum.
 Step 6: If sum is greater than target, move right pointer left to decrease sum.
 Step 7: Skip duplicate elements to avoid adding duplicate pairs to result.
 Step 8: Continue until left pointer meets or crosses right pointer.

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