leetcode刷题笔记(Golang)--215. Kth Largest Element in an Array_golang215

215. Kth Largest Element in an Array

nd 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

func findKthLargest(nums []int, k int) int {
	l:=0
	r:= len(nums)-1
	for {
		pos := partition(&nums,l,r)
		if pos == k-1 {
			return nums[pos]
		} else if pos > k-1 {
			r = pos-1
		} else {
			l = pos + 1
		}
	}
}

func partition(nums *[]int,l int, r int) int {
    pivot := (*nums)[l]
    pIndex := l
    l++
	for l <= r {
		if (*nums)[l] < pivot && (*nums)[r] > pivot {
			(*nums)[l], (*nums)[r] = (*nums)[r],(*nums)[l]
		}
		if (*nums)[l] >= pivot {
			l++
		}
		if (*nums)[r] <= pivot {
			r--
		}
	}
	(*nums)[pIndex], (*nums)[r] = (*nums)[r],(*nums)[pIndex]
	return r
}
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