Two Pointers
ProUse when you need to find a pair or compare elements from opposite ends of a sorted or structured input efficiently in O(n) time.
Use when you have a sorted (or structured) input and need to find or compare elements from opposite ends, converging inward in O(n) time.
Keywords for identifying Two Pointer Problems
→ Sorted array + find pair / triplet with a target sum
→ Palindrome check (compare from both ends)
→ Compare / merge from both ends
→ "Two sum" variant on sorted input
→ Maximize / minimize with width × height
→ Pair heaviest with lightest (greedy pairing)
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