<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>

class Solution {
public:
    int findKthLargest(vector<int>& nums, int k) {
        std::random_device rnd;
        mt.seed(rnd());
        int left = 0;
        int right = nums.size() - 1;
        k = nums.size() - k;
        while(true){
            int pivot_index = quickSelect(left, right, nums);
            if (pivot_index < k){
                left = pivot_index + 1;
            } else if (pivot_index > k){
                right = pivot_index - 1;
            } else {
                break;
            }
        }
        return nums[k];
    }

    int quickSelect(int left, int right, vector<int> & nums){
        std::uniform_int_distribution<> rand(left, right);
        int pivot_index = rand(mt);//left + (rand(mt) % (right - left + 1));
        int pivot_value = nums[pivot_index];
        swap(nums[pivot_index], nums[right]);
        for(int index = left; index < right; index++){
            if (nums[index] < pivot_value){
                swap(nums[left++], nums[index]);
            }
        }
        swap(nums[left], nums[right]);
        return left;
    }

std::mt19937 mt;
};
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