LeetCode in Kotlin

459. Repeated Substring Pattern

Easy

Given a string s, check if it can be constructed by taking a substring of it and appending multiple copies of the substring together.

Example 1:

Input: s = “abab”

Output: true

Explanation: It is the substring “ab” twice.

Example 2:

Input: s = “aba”

Output: false

Example 3:

Input: s = “abcabcabcabc”

Output: true

Explanation: It is the substring “abc” four times or the substring “abcabc” twice.

Constraints:

• 1 <= s.length <= 104
• s consists of lowercase English letters.

Solution

class Solution {
    fun repeatedSubstringPattern(s: String): Boolean {
        val n = s.length
        if (n < 2) {
            return false
        }
        var i = 0
        while (i < (n + 1) / 2) {
            if (n % (i + 1) != 0) {
                i++
                continue
            }
            var match = true
            val substring = s.substring(0, i + 1)
            var skippedI = i
            var j = i + 1
            while (j < n) {
                if (s.substring(j, j + i + 1) != substring) {
                    match = false
                    break
                }
                skippedI += i + 1
                j += i + 1
            }
            if (match) {
                return true
            }
            i = skippedI
            i++
        }
        return false
    }
}

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