0859. Buddy Strings

https://leetcode.com/problems/buddy-strings

Description

Given two strings s and goal, return true if you can swap two letters in s so the result is equal to goal, otherwise, return false.

Swapping letters is defined as taking two indices i and j (0-indexed) such that i != j and swapping the characters at s[i] and s[j].

• For example, swapping at indices 0 and 2 in "abcd" results in "cbad".

Example 1:

**Input:** s = "ab", goal = "ba"
**Output:** true
**Explanation:** You can swap s[0] = 'a' and s[1] = 'b' to get "ba", which is equal to goal.

Example 2:

**Input:** s = "ab", goal = "ab"
**Output:** false
**Explanation:** The only letters you can swap are s[0] = 'a' and s[1] = 'b', which results in "ba" != goal.

Example 3:

**Input:** s = "aa", goal = "aa"
**Output:** true
**Explanation:** You can swap s[0] = 'a' and s[1] = 'a' to get "aa", which is equal to goal.

Example 4:

**Input:** s = "aaaaaaabc", goal = "aaaaaaacb"
**Output:** true

Constraints:

• 1 <= s.length, goal.length <= 2 * 104

• s and goal consist of lowercase letters.

ac