Pattern concept

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Code snippets

How to identify

Does the problem involve any of these?

• Searching for pairs or triplets of elements that satisfy certain conditions
  • Sum of Three: Find triplets that sum up to a target.
  • Best Time to Buy and Sell Stock: Find a pair of elements with max profit.
• Maintaining two pointers to scan a list simultaneously from both ends
  • Valid Palindrome: Check whether a string is a valid palindrome.
  • Valid Palindrome II: Check whether a string is almost a valid palindrome.
  • Trapping Rain Water: Scan the list to calculate the amount of rainwater that can be trapped.
• Maintaining a sliding window or range within the array or list (covered later)
• Manipulating pointers to nodes in a linked list or tree (covered later)
• merging or comparing two sorted lists (covered later)