LeetCode | 0153. 寻找旋转排序数组中的最小值【Python】

LeetCode 0153. Find Minimum in Rotated Sorted Array寻找旋转排序数组中的最小值【Medium】【Python】【二分】

Problem

LeetCode

Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.

(i.e., [0,1,2,4,5,6,7] might become [4,5,6,7,0,1,2]).

Find the minimum element.

You may assume no duplicate exists in the array.

Example 1:

Input: [3,4,5,1,2] 
Output: 1

Example 2:

Input: [4,5,6,7,0,1,2]
Output: 0

问题

力扣

假设按照升序排序的数组在预先未知的某个点上进行了旋转。

( 例如，数组 [0,1,2,4,5,6,7] 可能变为 [4,5,6,7,0,1,2] )。

请找出其中最小的元素。

你可以假设数组中不存在重复元素。

示例 1:

输入: [3,4,5,1,2]
输出: 1

示例 2:

输入: [4,5,6,7,0,1,2]
输出: 0

思路

二分查找

看到有序的数组就想到二分查找。
nums[mid] <= nums[high]: 表示在 mid 左侧
nums[mid] > nums[high]: 表示在 mid 右侧

时间复杂度: O(logn)
空间复杂度: O(1)

Python代码

class Solution(object):
    def findMin(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        low, high = 0, len(nums) - 1
        while low < high:  # < not <=, or <= will TLE
            mid = int((low + high) / 2)
            if nums[mid] <= nums[high]:  # <=
                high = mid  # h = m not m - 1
            else:
                low = mid + 1
        return nums[low]

代码地址

GitHub链接