LeetCode | 0153. Find Minimum in Rotated Sorted Array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