1234. Replace the Substring for Balanced String

You are given a string s of length n containing only four kinds of characters: 'Q', 'W', 'E', and 'R'. A string is said to be balanced if each of its characters appears n / 4 times where n is the length of the string. Return the minimum length of the substring that can be replaced with any other string of the same length to make s balanced. If s is already balanced, return 0. Example 1: Inpu