package q215

func findKthLargest(nums []int, k int) int {
	// build max-heap
	for i := 1; i < len(nums); i++ {
		for j := i; j > 0; j = (j - 1) / 2 {
			parent := (j - 1) / 2
			if nums[j] > nums[parent] {
				nums[j], nums[parent] = nums[parent], nums[j]
			}
		}
	}

	for range k - 1 {
		// pop the heap
		nums[0] = nums[len(nums)-1]
		nums = nums[:len(nums)-1]

		i := 0
		for i*2+1 < len(nums) {
			l, r := i*2+1, i*2+2
			next := l
			if r < len(nums) && nums[r] > nums[l] {
				next = r
			}
			if nums[i] >= nums[next] {
				break
			}
			nums[i], nums[next] = nums[next], nums[i]
			i = next
		}
	}

	return nums[0]
}

var _ = findKthLargest