[nakjun12] Week1

contains-duplicate/nakjun12.js

@@ -0,0 +1,7 @@
+/**
+ * @param {number[]} nums
+ * @return {boolean}
+ */
+var containsDuplicate = function (nums) {
+  return new Set(nums).size !== nums.length;
+};

longest-consecutive-sequence/nakjun12.ts

@@ -0,0 +1,25 @@
+/*
+ * TC: O(n)
+ * SC: O(n)
+ * */
+function longestConsecutive(nums: number[]): number {
+  if (nums.length === 0) return 0;
+
+  const numSet = new Set(nums);
+  let longest = 0;
+
+  for (const num of nums) {
+    if (numSet.has(num - 1)) {
+      continue;
+    }
+
+    let length = 1;
+    while (numSet.has(num + length)) {
+      length++;
+    }
+
+    longest = Math.max(length, longest);
+  }
+
+  return longest;
+}

top-k-frequent-elements/nakjun12.ts

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+function topKFrequent(nums: number[], k: number): number[] {
+  const frequency = nums.reduce(
+    (acc, n) => acc.set(n, (acc.get(n) ?? 0) + 1),
+    new Map<number, number>()
+  );
+
+  return Array.from(frequency)
+    .sort((a, b) => b[1] - a[1])
+    .slice(0, k)
+    .map((item) => item[0]);
+}

valid-palindrome/nakjun12.ts

@@ -0,0 +1,11 @@
+function isPalindrome(s: string): boolean {
+  const convertWord = s.toLowerCase().match(/[a-z0-9]/g) ?? [];
+  const length = convertWord.length;
+  for (let i = 0; i < length / 2; i++) {
+    if (convertWord[i] !== convertWord[length - 1 - i]) {
+      return false;
+    }
+  }
+
+  return true;
+}