solve: longest palindromic substring

Author: wogha95

longest-palindromic-substring/wogha95.js

@@ -0,0 +1,38 @@
+/**
+ * TC: O(N^2)
+ * 주어진 s 문자열이 한 종류의 문자로 이루어져있다면 for문에서 O(N), while문에서 O(N) 이므로 O(N * 2N)
+ *
+ * SC: O(1)
+ */
+
+/**
+ * @param {string} s
+ * @return {string}
+ */
+var longestPalindrome = function (s) {
+  let result = "";
+
+  for (let index = 0; index < s.length; index++) {
+    const [start1, end1] = getPalindromicSubstringLength(index, index);
+    const [start2, end2] = getPalindromicSubstringLength(index, index + 1);
+
+    if (result.length < end1 - start1 + 1) {
+      result = s.substring(start1, end1 + 1);
+    }
+
+    if (result.length < end2 - start2 + 1) {
+      result = s.substring(start2, end2 + 1);
+    }
+  }
+
+  return result;
+
+  function getPalindromicSubstringLength(start, end) {
+    while (0 <= start && end < s.length && s[start] === s[end]) {
+      start -= 1;
+      end += 1;
+    }
+
+    return [start + 1, end - 1];
+  }
+};