top k frequent elements solution

Author: yoon-turtle

top-k-frequent-elements/yoonthecoder.js

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+var topKFrequent = function (nums, k) {
+  // 1. count the frequency of each number in the array
+  const map = new Map();
+
+  // iterating through the array to count how many times each num appears.
+  for (const num of nums) {
+    // if the num already exists in the map, increment its count
+    if (map.has(num)) {
+      map.set(num, map.get(num) + 1);
+    } // otherwise, set it to 1
+    else map.set(num, 1);
+  }
+
+  // 2.create an array to store the freqeuncy numbers
+  const freqArr = [];
+  for (const [num, freq] of map) {
+    freqArr.push([num, freq]);
+  }
+  // sort in descending order by frequency
+  freqArr.sort((a, b) => b[1] - a[1]);
+  return freqArr.slice(0, k).map(([num]) => num);
+};
+
+// Time complexity: O(nlogn)
+// Space complexity: O(n)