LeetCode 215. Kth Largest Element in an Array [Heap] Java


Find the kth largest element in an unsorted array. Note that it is the kth largest element in the sorted order, not the kth distinct element.

Example 1:

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

Example 2:

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

You may assume k is always valid, 1 ≤ k ≤ array’s length.

I have two solutions.

First one is simple, just two lines, first sort, then output the kth element.

Second is not hard too, first I build a max-heap, then output the kth element. (codes about max-heap see this)


Want to know more details of heap and heapsort, check my post:Heap and Heap-Sort algorithm.

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