力扣 215. 数组中第K个最大元素

无脑解法,根本思想是排序解决

def findKthLargest(nums, k):
    nums.sort()
    return nums[-k]

大顶堆

def findKthLargest(nums, k):
    # 以大顶堆实现
    nums_len= len(nums)

    # 建堆处理
    for i in range(1, nums_len):
        # 父节点
        j = (i - 1) >> 1
        while i > 0:
            if nums[i] > nums[j]:
                nums[i], nums[j] = nums[j], nums[i]
            i, j = j, (j - 1) >> 1
    # print(nums)
    # 堆排序
    nums_len -= 1
    for _ in range(k - 1):
        nums[0], nums[nums_len] = nums[nums_len], nums[0]
        nums_len -= 1
        j = 0
        while j <= nums_len:
            l, r, i = 2 * j + 1, 2 * j + 2, j
            if l <= nums_len and nums[l] > nums[i]:
                i = l
            if r <= nums_len and nums[r] > nums[i]:
                i = r
            if i != j:
                nums[i], nums[j] = nums[j], nums[i]
                j = i
            else:
                break

        # print(nums)
    return nums[0]