Time: 215 ms (71.29%), Space: 40.7 MB (13.52%) - LeetHub

Author: hajin-kim

0005-longest-palindromic-substring/0005-longest-palindromic-substring.kt

@@ -0,0 +1,41 @@
+class Solution {
+    private fun getPalindromeFrom(start: Int, end: Int, s: String, indices: IntRange): Pair<Int, Int> {
+        var nextStart = start
+        var nextEnd = end
+        while (nextStart in indices &&
+            nextEnd in indices &&
+            s[nextStart] == s[nextEnd]
+        ) {
+            --nextStart
+            ++nextEnd
+        }
+
+        return nextStart + 1 to nextEnd - 1
+    }
+
+    fun longestPalindrome(s: String): String {
+        val indices = s.indices
+
+        var maxRange = 0..0
+        var maxLength = 1
+
+        fun getPalindromeFrom(start: Int, end: Int) =
+            getPalindromeFrom(start, end, s, indices)
+
+        for (i in indices) {
+            listOf(
+                getPalindromeFrom(i, i),
+                getPalindromeFrom(i, i + 1),
+            ).forEach { (start, end) ->
+                val length = end - start + 1
+                if (length > maxLength) {
+                    maxLength = length
+                    maxRange = start..end
+                }
+            }
+
+        }
+
+        return s.slice(maxRange)
+    }
+}