Kth Largest Element in an Array LeetCode Solution

Here, We see Kth Largest Element in an Array LeetCode Solution. This Leetcode problem is done in many programming languages like C++, Java, JavaScript, Python, etc. with different approaches.

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Kth Largest Element in an Array LeetCode Solution

Kth Largest Element in an Array LeetCode Solution

Problem Statement

Given an integer array nums and an integer k, return the kth largest element in the array.

Note that it is the kth largest element in the sorted order, not the kth distinct element.

Can you solve it without sorting?

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

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

Kth Largest Element in an Array LeetCode Solution C++

class Solution {
public:
    int findKthLargest(std::vector<int>& nums, int k) {
        int left = 0, right = nums.size() - 1;
        while (true) {
            int pivot_index = rand() % (right - left + 1) + left;
            int new_pivot_index = partition(nums, left, right, pivot_index);
            if (new_pivot_index == nums.size() - k) {
                return nums[new_pivot_index];
            } else if (new_pivot_index > nums.size() - k) {
                right = new_pivot_index - 1;
            } else {
                left = new_pivot_index + 1;
            }
        }
    }

private:
    int partition(std::vector<int>& nums, int left, int right, int pivot_index) {
        int pivot = nums[pivot_index];
        std::swap(nums[pivot_index], nums[right]);
        int stored_index = left;
        for (int i = left; i < right; i++) {
            if (nums[i] < pivot) {
                std::swap(nums[i], nums[stored_index]);
                stored_index++;
            }
        }
        std::swap(nums[right], nums[stored_index]);
        return stored_index;
    }
};Code language: PHP (php)

Kth Largest Element in an Array LeetCode Solution Java

public class Solution {
    public int findKthLargest(int[] nums, int k) {
        int left = 0, right = nums.length - 1;
        Random rand = new Random();
        while (true) {
            int pivot_index = left + rand.nextInt(right - left + 1);
            int new_pivot_index = partition(nums, left, right, pivot_index);
            if (new_pivot_index == nums.length - k) {
                return nums[new_pivot_index];
            } else if (new_pivot_index > nums.length - k) {
                right = new_pivot_index - 1;
            } else {
                left = new_pivot_index + 1;
            }
        }
    }

    private int partition(int[] nums, int left, int right, int pivot_index) {
        int pivot = nums[pivot_index];
        swap(nums, pivot_index, right);
        int stored_index = left;
        for (int i = left; i < right; i++) {
            if (nums[i] < pivot) {
                swap(nums, i, stored_index);
                stored_index++;
            }
        }
        swap(nums, right, stored_index);
        return stored_index;
    }

    private void swap(int[] nums, int i, int j) {
        int temp = nums[i];
        nums[i] = nums[j];
        nums[j] = temp;
    }
}Code language: PHP (php)

Kth Largest Element in an Array Solution JavaScript

var findKthLargest = function(nums, k) {
    const partition = (left, right, pivotIndex) => {
        const pivot = nums[pivotIndex];
        [nums[pivotIndex], nums[right]] = [nums[right], nums[pivotIndex]];
        let storedIndex = left;
        for (let i = left; i < right; i++) {
            if (nums[i] < pivot) {
                [nums[storedIndex], nums[i]] = [nums[i], nums[storedIndex]];
                storedIndex++;
            }
        }
        [nums[right], nums[storedIndex]] = [nums[storedIndex], nums[right]];
        return storedIndex;
    };
    
    let left = 0, right = nums.length - 1;
    while (true) {
        const pivotIndex = left + Math.floor(Math.random() * (right - left + 1));
        const newPivotIndex = partition(left, right, pivotIndex);
        if (newPivotIndex === nums.length - k) {
            return nums[newPivotIndex];
        } else if (newPivotIndex > nums.length - k) {
            right = newPivotIndex - 1;
        } else {
            left = newPivotIndex + 1;
        }
    }
};Code language: JavaScript (javascript)

Kth Largest Element in an Array Solution Python

class Solution:
    def findKthLargest(self, nums, k):
        left, right = 0, len(nums) - 1
        while True:
            pivot_index = random.randint(left, right)
            new_pivot_index = self.partition(nums, left, right, pivot_index)
            if new_pivot_index == len(nums) - k:
                return nums[new_pivot_index]
            elif new_pivot_index > len(nums) - k:
                right = new_pivot_index - 1
            else:
                left = new_pivot_index + 1

    def partition(self, nums, left, right, pivot_index):
        pivot = nums[pivot_index]
        nums[pivot_index], nums[right] = nums[right], nums[pivot_index]
        stored_index = left
        for i in range(left, right):
            if nums[i] < pivot:
                nums[i], nums[stored_index] = nums[stored_index], nums[i]
                stored_index += 1
        nums[right], nums[stored_index] = nums[stored_index], nums[right]
        return stored_indexCode language: HTML, XML (xml)
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