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Change Minimum Characters to Satisfy One of Three Conditions | CodeTutor

Change Minimum Characters to Satisfy One of Three Conditions

Medium

Strings Hash Tables Prefix Sum

Problem

You are given two strings a and b that consist of lowercase letters. In one operation, you can change any character in a or b to any lowercase letter.

Your goal is to satisfy one of the following three conditions:

Every letter in a is strictly less than every letter in b in the alphabet.
Every letter in b is strictly less than every letter in a in the alphabet.
Both a and b consist of only one distinct letter.

Return the minimum number of operations needed to achieve your goal.

Constraints

1 <= a.length, b.length <= 10^5
a and b consist only of lowercase letters.

Examples

Input: a = "aba", b = "caa"

Output: 2

Consider the best way to make each condition true: 1) Change b to "ccc" in 2 operations, then every letter in a is less than every letter in b. 2) Change a to "bbb" and b to "aaa" in 3 operations, then every letter in b is less than every letter in a. 3) Change a to "aaa" and b to "aaa" in 2 operations, then a and b consist of one distinct letter. The best way was done in 2 operations (either condition 1 or condition 3).

Input: a = "dabadd", b = "cda"

Output: 3

The best way is to make condition 1 true by changing b to "eee".

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