LeetCode in Kotlin

859. Buddy Strings

Easy

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.

Constraints:

• 1 <= s.length, goal.length <= 2 * 104
• s and goal consist of lowercase letters.

Solution

class Solution {
    fun buddyStrings(s: String, goal: String): Boolean {
        var first = -1
        val second: Int
        val sCounts = IntArray(26)
        if (s == goal) {
            for (i in s.indices) {
                sCounts[s[i].code - 'a'.code]++
                if (sCounts[s[i].code - 'a'.code] > 1) {
                    return true
                }
            }
        }
        for (i in s.indices) {
            val curr = s[i]
            sCounts[curr.code - 'a'.code]++
            if (curr != goal[i]) {
                if (first == -1) {
                    first = i
                } else {
                    second = i
                    val ss = s.toCharArray()
                    val temp = ss[first]
                    ss[first] = ss[second]
                    ss[second] = temp
                    return String(ss) == goal
                }
            }
        }
        return false
    }
}

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