longest palindromic substring solution

Author: hyer0705

longest-palindromic-substring/hyer0705.ts

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+// Time Complexity: O(n^2), n: s의 길이
+// Space Complexity: O(1)
+function longestPalindrome(s: string): string {
+  const expandAroundCenter = (s: string, left: number, right: number): [number, number] => {
+    while (left >= 0 && right < s.length && s[left] === s[right]) {
+      left--;
+      right++;
+    }
+
+    return [left + 1, right - 1];
+  };
+
+  let longest = "";
+  for (let i = 0; i < s.length; i++) {
+    const [s1, e1] = expandAroundCenter(s, i, i);
+    const [s2, e2] = expandAroundCenter(s, i, i + 1);
+
+    const odd = e1 - s1 + 1;
+    const even = e2 - s2 + 1;
+
+    if (longest.length < odd) {
+      longest = s.slice(s1, e1 + 1);
+    }
+
+    if (longest.length < even) {
+      longest = s.slice(s2, e2 + 1);
+    }
+  }
+
+  return longest;
+}