Golang | Leetcode Golang题解之第215题数组中的第K个最大元素_golang leetcode 数组中的第k个最大元素

题目：

题解：

func findKthLargest(nums []int, k int) int {
    heapSize := len(nums)
    buildMaxHeap(nums, heapSize)
    for i := len(nums) - 1; i >= len(nums) - k + 1; i-- {
        nums[0], nums[i] = nums[i], nums[0]
        heapSize--
        maxHeapify(nums, 0, heapSize)
    }
    return nums[0]
}
 
func buildMaxHeap(a []int, heapSize int) {
    for i := heapSize/2; i >= 0; i-- {
        maxHeapify(a, i, heapSize)
    }
}
 
func maxHeapify(a []int, i, heapSize int) {
    l, r, largest := i * 2 + 1, i * 2 + 2, i
    if l < heapSize && a[l] > a[largest] {
        largest = l
    }
    if r < heapSize && a[r] > a[largest] {
        largest = r
    }
    if largest != i {
        a[i], a[largest] = a[largest], a[i]
        maxHeapify(a, largest, heapSize)
    }
}