easyTwo PointersPattern: Two Pointers
Pairwise Sum Equality Solution
Problem Statement
Given an array of integers and a target sum, determine if there exist two elements in the array that add up to the target sum.
Examples
Example 1:
Input:[1, 2, 3, 4, 5], 7
Output:True
Explanation: The elements at indices 2 and 4 add up to the target sum of 7 (3 + 4 = 7).
Example 2:
Input:[10, 20, 30], 5
Output:False
Explanation: No two elements in the array add up to the target sum of 5.
Constraints
- Array size is at most 10^4
- Target sum is a positive integer
- Array elements are distinct integers
- All elements in the array are non-negative
Time: O(n log n) Space: O(1)
The optimal approach is to sort the array and then use two pointers, one starting from the beginning and one from the end of the array, to find a pair of elements that add up to the target sum in linear time.
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