Solving Longest Valid Parentheses, Trapping Rain Water, and Wildcard Matching Problems
Longest Valid Parentheses
Given a string containing only '(' and ')', find the length of the longest valid (well-formed and contiguous) parentheses substring.
Dynamic Programming Solution
Define dp[i] as the length of the longest valid parentheses ending at position i. To each character at index i:
If s[i] is '(', set dp[i] = 0
If s[i] is ')', ...
Posted on Sat, 16 May 2026 08:12:44 +0000 by mitchell_1078
Fixed-Size Sliding Window Technique for Identifying String Anagrams
Problem Definition
Given two strings s and p, identify every starting index within s where a substring contains the exact same characters as p with identical frequencies. Character order is irrelevant for matching purposes.
Example: With s = "cbaebabacd" and p = "abc", the qualifying substrings apppear at indices 0 ("cb ...
Posted on Thu, 14 May 2026 07:21:00 +0000 by onyx