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
Input
s = "QWER"Output
0s is already balanced.
Example 2
Input
s = "QQWE"Output
1We need to replace a 'Q' to 'R', so that "RQWE" (or "QRWE") is balanced.
Constraints
- n == s.length
- 4 <= n <= 10^5
- n is a multiple of 4.
- s contains only 'Q', 'W', 'E', and 'R'.