# Kth Largest Element in an Array – LeetCode Solution Java , Python 3, Python 2 , C , C++, Best and Optimal Solutions , All you need.

Given an integer array `nums`

and an integer `k`

, return *the* `k`

^{th}*largest element in the array*.

Note that it is the `k`

largest element in the sorted order, not the ^{th}`k`

distinct element.^{th}

You must solve it in `O(n)`

time complexity.

**Example 1:**

Input:nums = [3,2,1,5,6,4], k = 2Output:5

**Example 2:**

Input:nums = [3,2,3,1,2,4,5,5,6], k = 4Output:4

**Constraints:**

`1 <= k <= nums.length <= 10`

^{5}`-10`

^{4}<= nums[i] <= 10^{4}

# C++ Kth Largest Element in an Array LeetCode Solution

```
```**Quickselect**

```
int findKthLargest(vector<int>& nums, int k) {
//partition rule: >=pivot pivot <=pivot
int left=0,right=nums.size()-1,idx=0;
while(1){
idx = partition(nums,left,right);
if(idx==k-1) break;
else if(idx < k-1) left=idx+1;
else right= idx-1;
}
return nums[idx];
}
int partition(vector<int>& nums,int left,int right){//hoare partition
int pivot = nums[left], l=left+1, r = right;
while(l<=r){
if(nums[l]<pivot && nums[r]>pivot) swap(nums[l++],nums[r--]);
if(nums[l]>=pivot) ++l;
if(nums[r]<=pivot) --r;
}
swap(nums[left], nums[r]);
return r;
}
```

# Java Kth Largest Element in an Array LeetCode Solution

```
``````
public class Solution {
public int findKthLargest(int[] nums, int k) {
int start = 0, end = nums.length - 1, index = nums.length - k;
while (start < end) {
int pivot = partion(nums, start, end);
if (pivot < index) start = pivot + 1;
else if (pivot > index) end = pivot - 1;
else return nums[pivot];
}
return nums[start];
}
private int partion(int[] nums, int start, int end) {
int pivot = start, temp;
while (start <= end) {
while (start <= end && nums[start] <= nums[pivot]) start++;
while (start <= end && nums[end] > nums[pivot]) end--;
if (start > end) break;
temp = nums[start];
nums[start] = nums[end];
nums[end] = temp;
}
temp = nums[end];
nums[end] = nums[pivot];
nums[pivot] = temp;
return end;
}
}
```

# Python 3 Kth Largest Element in an Array LeetCode Solution

```
``````
class Solution:
def findKthLargest(self, nums, k):
if not nums: return
pivot = random.choice(nums)
left = [x for x in nums if x > pivot]
mid = [x for x in nums if x == pivot]
right = [x for x in nums if x < pivot]
L, M = len(left), len(mid)
if k <= L:
return self.findKthLargest(left, k)
elif k > L + M:
return self.findKthLargest(right, k - L - M)
else:
return mid[0]
```

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