【刷题-LeetCode】153 Find Minimum in Rotated Sorted Array

153. Find Minimum in Rotated Sorted Array

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

解 二分查找

class Solution {
public:
    int findMin(vector<int>& nums) {
        // 特殊情况
        if(nums.size() == 1)return nums[0];
        int l = 0, r = nums.size()-1, mid;
        if(nums[r] > nums[l])return nums[l];
        //查找
        while(l <= r){
            mid = (l+r)/2;
            //两种情况对应着断点
            if(nums[mid] > nums[mid+1])return nums[mid+1];
            if(nums[mid-1] > nums[mid])return nums[mid];
            //调整两侧的范围
            if(nums[mid] > nums[0]){
                l = mid + 1;
            }else{
                r = mid - 1;
            }
        }
        return -1;
    }
};