LeetCode-in-All

215. Kth Largest Element in an Array

Medium

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.

You must solve it in O(n) time complexity.

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

Constraints:

• 1 <= k <= nums.length <= 105
• -104 <= nums[i] <= 104

Solution

impl Solution {
    pub fn find_kth_largest(nums: Vec<i32>, mut k: i32) -> i32 {
        const NEGATIVE_OFFSET: usize = 10_000;

        let mut freq_array = [0; 20_001];
        for n in nums {
            freq_array[n as usize + NEGATIVE_OFFSET] += 1;
        }

        for i in (0..freq_array.len()).rev() {
            k -= freq_array[i];
            if k <= 0 {
                return (i - NEGATIVE_OFFSET) as i32;
            }
        }

        0
    }
}

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