Kth Largest Element in an Array
<p>Given an integer array <code>nums</code> and an integer <code>k</code>, return <em>the</em> <code>k<sup>th</sup></code> <em>largest element in the array</em>.</p>

<p>Note that it is the <code>k<sup>th</sup></code> largest element in the sorted order, not the <code>k<sup>th</sup></code> distinct element.</p>

<p>Can you solve it without sorting?</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<pre><strong>Input:</strong> nums = [3,2,1,5,6,4], k = 2
<strong>Output:</strong> 5
</pre><p><strong class="example">Example 2:</strong></p>
<pre><strong>Input:</strong> nums = [3,2,3,1,2,4,5,5,6], k = 4
<strong>Output:</strong> 4
</pre>
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= k &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
</ul>
Array; Divide and Conquer; Quickselect; Sorting; Heap (Priority Queue)
class Solution {
    private int[] nums;
    private int k;

    public int findKthLargest(int[] nums, int k) {
        this.nums = nums;
        this.k = nums.length - k;
        return quickSort(0, nums.length - 1);
    }

    private int quickSort(int l, int r) {
        if (l == r) {
            return nums[l];
        }
        int i = l - 1, j = r + 1;
        int x = nums[(l + r) >>> 1];
        while (i < j) {
            while (nums[++i] < x) {
            }
            while (nums[--j] > x) {
            }
            if (i < j) {
                int t = nums[i];
                nums[i] = nums[j];
                nums[j] = t;
            }
        }
        if (j < k) {
            return quickSort(j + 1, r);
        }
        return quickSort(l, j);
    }
}
