top-k-frequent-elements

Author: taewanseoul

top-k-frequent-elements/taewanseoul.ts

@@ -0,0 +1,31 @@
+/**
+ * 347. Top K Frequent Elements
+ * Given an integer array nums and an integer k, return the k most frequent elements. You may return the answer in
+ * any order.
+ * https://leetcode.com/problems/top-k-frequent-elements/description/
+ */
+function topKFrequent(nums: number[], k: number): number[] {
+  const map = new Map<number, number>();
+
+  nums.forEach((n) => {
+    const count = map.get(n);
+    if (count) {
+      map.set(n, count + 1);
+      return;
+    }
+    map.set(n, 1);
+  });
+
+  const kvArray = [...map];
+  const sorted = kvArray.sort(([, v1], [, v2]) => v2 - v1);
+
+  const result: number[] = [];
+  for (let i = 0; i < k; i++) {
+    result.push(sorted[i][0]);
+  }
+
+  return result;
+}
+
+// O(n) time
+// O(n) space