leetcode 153 : Find Minimum in Rotated Sorted Array

Suppose a sorted array 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.

代码

class Solution {
public:
    int findMin(vector<int>& nums) {
        int low=0,high=nums.size()-1,middle;
        while(low<=high){               //low<=high
            middle=(low+high)/2;
            if(nums[middle]<nums[high]){
                high=middle;            //不是middle＋1
            }else if(nums[middle]>nums[high]){
                low=middle+1;
            }else{              
                return nums[high];
            }
        }
        return nums[high];
    }
};

代码更精简的版本：

class Solution {
public:
    int findMin(vector<int>& nums) {
        int low=0,high=nums.size()-1,middle;

        //保证得到，low=middle+1
        while(low<high){            //low<high
            middle=(low+high)/2;
            if(nums[middle]<=nums[high]){
                high=middle;        //不是middle＋1，所以while条件时low<high
            }else{
                low=middle+1;
            }
        }
        return nums[high];
    }
};