409. Longest Palindrome (axross#116)

Author: Kohei Asai

Diff for: solutions/longestPalindrome.test.ts

@@ -0,0 +1,20 @@
+import longestPalindrome from "./longestPalindrome";
+
+describe("409. Longest Palindrome", () => {
+  const TEST_CASES = new Map([
+    ["abccccdd", 7],
+    ["bb", 2],
+    ["aaaAaaaa", 7],
+    ["zeusnilemacaronimaisanitratetartinasiaminoracamelinsuez", 55],
+    [
+      "civilwartestingwhetherthatnaptionoranynartionsoconceivedandsodedicatedcanlongendureWeareqmetonagreatbattlefiemldoftzhatwarWehavecometodedicpateaportionofthatfieldasafinalrestingplaceforthosewhoheregavetheirlivesthatthatnationmightliveItisaltogetherfangandproperthatweshoulddothisButinalargersensewecannotdedicatewecannotconsecratewecannothallowthisgroundThebravelmenlivinganddeadwhostruggledherehaveconsecrateditfaraboveourpoorponwertoaddordetractTgheworldadswfilllittlenotlenorlongrememberwhatwesayherebutitcanneverforgetwhattheydidhereItisforusthelivingrathertobededicatedheretotheulnfinishedworkwhichtheywhofoughtherehavethusfarsonoblyadvancedItisratherforustobeherededicatedtothegreattdafskremainingbeforeusthatfromthesehonoreddeadwetakeincreaseddevotiontothatcauseforwhichtheygavethelastpfullmeasureofdevotionthatweherehighlyresolvethatthesedeadshallnothavediedinvainthatthisnationunsderGodshallhaveanewbirthoffreedomandthatgovernmentofthepeoplebythepeopleforthepeopleshallnotperishfromtheearth",
+      983
+    ]
+  ]);
+
+  for (const [s, expected] of TEST_CASES) {
+    it(`returns ${expected} when called with ${s}`, () => {
+      expect(longestPalindrome(s)).toBe(expected);
+    });
+  }
+});

Diff for: solutions/longestPalindrome.ts

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+// 409. Longest Palindrome
+// https://leetcode.com/problems/longest-palindrome/
+export default function longestPalindrome(s: string): number {
+  const oddChars = new Set<number>();
+  let count = 0;
+
+  for (let i = 0; i < s.length; ++i) {
+    const char = s.charCodeAt(i);
+
+    if (oddChars.has(char)) {
+      oddChars.delete(char);
+
+      count += 2;
+    } else {
+      oddChars.add(char);
+    }
+  }
+
+  return count + (oddChars.size >= 1 ? 1 : 0);
+}