LeetCode in Kotlin

2840. Check if Strings Can be Made Equal With Operations II

Medium

You are given two strings s1 and s2, both of length n, consisting of lowercase English letters.

You can apply the following operation on any of the two strings any number of times:

• Choose any two indices i and j such that i < j and the difference j - i is even, then swap the two characters at those indices in the string.

Return true if you can make the strings s1 and s2 equal, andfalse otherwise.

Example 1:

Input: s1 = “abcdba”, s2 = “cabdab”

Output: true

Explanation: We can apply the following operations on s1:

• Choose the indices i = 0, j = 2. The resulting string is s1 = “cbadba”.
• Choose the indices i = 2, j = 4. The resulting string is s1 = “cbbdaa”.
• Choose the indices i = 1, j = 5. The resulting string is s1 = “cabdab” = s2.

Example 2:

Input: s1 = “abe”, s2 = “bea”

Output: false

Explanation: It is not possible to make the two strings equal.

Constraints:

• n == s1.length == s2.length
• 1 <= n <= 105
• s1 and s2 consist only of lowercase English letters.

Solution

class Solution {
    fun checkStrings(s1: String, s2: String): Boolean {
        return check(0, s1, s2) && check(1, s1, s2)
    }

    fun check(start: Int, s1: String, s2: String): Boolean {
        val step = 2
        val buf = IntArray(26)
        var i = start
        while (i < s1.length) {
            buf[s1[i].code - 'a'.code]++
            buf[s2[i].code - 'a'.code]--
            i += step
        }
        for (j in buf) {
            if (j != 0) {
                return false
            }
        }
        return true
    }
}

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