Solving the coding problem: Minimum Window Substring (Leetcode 76)

Given a string S and a string T, find the minimum window in S which will contain all the characters in T in complexity O(n).

Example:

Input: S = "ADOBECODEBANC", T = "ABC"
Output: "BANC"

I found interesting non-standard approach using just one pointer, which can solve that problem in O(N + M) time and O(M) space where N size of S and M size of T.

Idea is simply based on the fact that we can maintain position of each char at T and update it…