205.数组中的第k个最大元素

思路：partition函数

class Solution(object):
    def findKthLargest(self, nums, k):
        def partition(low,high):
            pivot = nums[low]
            while low<high:
                while low<high and nums[high]>=pivot:
                    high-=1
                nums[low] = nums[high]
                while low<high and nums[low]<=pivot:
                    low+=1
                nums[high]=nums[low]
            nums[low] = pivot
            return low
        left = 0
        right = len(nums) - 1
        t = len(nums)-k+1
        while True:
            idx = partition(left, right)
            if idx == t - 1:
                return nums[idx]
            if idx < t - 1:
                left = idx + 1
            if idx > t - 1:
                right = idx - 1