Create Top K Frequent Words.md

Author: cheatsheet1999

JS-Algo/Top K Frequent Words.md

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+#### Given an array of strings `words` and an integer `k`, return the `k` most frequent strings.
+
+Return the answer **sorted** by **the frequency** from highest to lowest. Sort the words with the same frequency by their **lexicographical order.**
+
+<img width="482" alt="Screen Shot 2021-11-07 at 11 40 52 PM" src="https://user-images.githubusercontent.com/37787994/140695569-19b04861-cb4a-484c-bcf5-0ee9961e77cb.png">
+
+```JS
+/**
+ * @param {string[]} words
+ * @param {number} k
+ * @return {string[]}
+ */
+//  O(n log n)
+var topKFrequent = function(words, k) {
+    const map = {};
+    for(let word of words) {
+        map[word] = map[word] + 1 || 1;
+    }
+    let res = Object.keys(map).sort((a, b) => {
+        let diff = map[b] - map[a];
+        if(diff === 0) {
+        /*
+        sorting descend in an alphabetic order. i.e. a -> b -> c -> d
+        localeCompare() returns one of 3 numbers indicating the sort order.
+         -1 if sorted before
+          1 if sorted after
+          0 if equal
+        */
+            return a.localeCompare(b);
+        }
+        else {
+            return diff;
+        }
+    })
+    return res.slice(0, k);
+};
+```