<pre class="shiki github-dark shaku"><code>/** * @param {number[]} arr * @param {number} k */function findKThLargest(arr, k) { // 左闭右开 const qsort = function(start, end) { let left = start; let right = end-1; const p = arr[right]; while(left&lt;right) { while(arr[left]&lt;p &amp;&amp; left&lt;right) {left++;} while(arr[right]&gt;=p &amp;&amp; left&lt;right) {right--;} if(left&lt;right) { const tmp = arr[left]; arr[left] = arr[right]; arr[right] = tmp; } } const tmp = arr[left]; arr[left] = arr[end-1]; arr[end-1] = tmp; return left; } // 左闭右开 let left = 0; let right = arr.length; while(left&lt;right) { const mid = qsort(left, right); if(mid===arr.length-k) { return arr[mid]; }else if(mid&gt;arr.length-k) { right = mid; }else { left = mid+1; } }}</code></pre>

qsort solution

You are given an unsorted array of numbers, which might have duplicates, find the K-th largest element. The naive approach would be sort it first, but…