<pre class="shiki github-dark shaku"><code>// complete the implementationclass PriorityQueue { /** * @param {(a: any, b: any) =&gt; -1 | 0 | 1} compare - * compare function, similar to parameter of Array.prototype.sort */ constructor(comparator = (a, b) =&gt; a - b) { this.data = []; this.comparator = comparator; } /** * return {number} amount of items */ size() { return this.data.length; } /** * returns the head element */ peek() { if(this.size() === 0) return undefined; return this.data[0]; } /** * @param {any} element - new element to add */ add(element) { this.data.push(element); this.upBubble(this.size() - 1); } /** * remove the head element * @return {any} the head element */ poll() { if(this.size() === 0) return undefined; const result = this.data[0]; const last = this.data.pop(); if(this.size() !== 0) { this.data[0] = last; this.downBubble(0); } return result; } upBubble(index) { while(index &gt; 0) { const parentIndex = Math.floor((index - 1) / 2); if(this.comparator(this.data[index], this.data[parentIndex]) &lt; 0) { this.swap(index, parentIndex); index = parentIndex; } else { break; } } } downBubble(index) { const lastIndex = this.size() - 1; while(true) { let leftIndex = index * 2 + 1; let rightIndex = index * 2 + 2; let findIndex = index; if(leftIndex &lt;= lastIndex &amp;&amp; this.comparator(this.data[leftIndex], this.data[findIndex]) &lt; 0) { findIndex = leftIndex; } if(rightIndex &lt;= lastIndex &amp;&amp; this.comparator(this.data[rightIndex], this.data[findIndex]) &lt; 0) { findIndex = rightIndex; } if(findIndex !== index) { this.swap(index, findIndex); index = findIndex; } else { break; } } } swap(idx1, idx2) { [this.data[idx1], this.data[idx2]] = [this.data[idx2], this.data[idx1]] }}</code></pre>

My solution

Priority Queue is a commonly used data structure in algorithm problem. Especially useful for Top K problem with a huge amount of input data, since it …