LeetCode 153. Find Minimum in Rotated Sorted Array

原题链接在这里：https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/description/

题目：

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.

题解：

Binary Search, 与Find Peak Element类似.

如果nums[mid] < nums[r]说明右边一段是sorted的, minumum 只能出现在包括中点的左边一段. 

反之, 说明左边一段是sorted的, minimum只能出现在不包括中点的右边一段.

最后返回nums[r].

Time Compelxity: O(logn). n = nums.length.

Space: O(1).

AC Java:

class Solution {
    public int findMin(int[] nums) {
        int l = 0;
        int r = nums.length - 1;
        while(l < r){
            int mid = l + (r - l) / 2;
            if(nums[mid] < nums[r]){
                r = mid;
            }else{
                l = mid + 1;
            }
        }
        
        return nums[l];
    }
}

类似Search in Rotated Sorted Array, Find Minimum in Rotated Sorted Array II, Single Element in a Sorted Array.