loading

Substring with Concatenation of All Words — Step-by-Step Visualization

hardLeetCode #30Hash TableStringSliding Window

You are given a string s and an array of strings words. All the strings of words are of the same length. Return all starting indices of substring(s) in s that is a concatenation of each word in words exactly once, in any order.

Algorithm Pattern

Sliding Window + Hash Map

Key Idea

At each position, split the window into word-sized chunks and compare frequency maps.

Step-by-Step Approach

  1. Build expected word frequency map
  2. Slide window of size wordLen*len(words)
  3. At each position, check if word chunks match expected frequencies

Related Problems

← All problems