leetcode33---Search in Rotated Sorted Array

问题描述：

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).

You are given a target value to search. If found in the array return its index, otherwise return -1.

You may assume no duplicate exists in the array.

特点：数组中没有重复数字

问题求解：

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