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Rahul Kumar Barnwal @rahulgithub-web

Substring With Concatenation Of All Words

Solve substring with concatenation of all words using sliding window & hash map. Precompute word frequencies, slide window, shrink or expand based on matches. Time complexity: O(n⋅k), space complexity: O(m+k).

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The Substring with Concatenation of All Words problem is a challenging sliding window and hash map problem. Let’s break it down step by step to solve it efficiently.


  
  
  🚀 Problem Description

Given a string s and an array of strings words:

Each word in words is of the same length.
A valid concatenated substring is a substring of s that contains all the strings from words concatenated in any order.
Return an array of the starting indices of all such substrings in s.



  
  
  💡 Examples

Example 1

Input: s = "barfoothefoobarman", words = ["foo", "bar"]  
Output: [0...