[LeetCode]Search in Rotated Sorted Array

Search 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).

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.

二分搜索，好好理解里面的逻辑吧。

 1 class Solution {
 2 public:
 3     int search(vector<int>& nums, int target) {
 4         if(nums.size()==0) return -1;
 5         int left=0,right=nums.size()-1;
 6         while(left<=right)
 7         {
 8             int mid = (left+right)/2;
 9             if(nums[mid]==target) return mid;
10             if(nums[mid]>nums[left])
11             {
12                 if(target <= nums[mid] && target >= nums[left]) right = mid - 1;
13                 else left = mid + 1;
14             }
15             else if(nums[mid]<nums[left])
16             {
17                 if(target >= nums[left] || target <= nums[mid]) right = mid -1;
18                 else left = mid + 1;
19             }
20             else left ++;
21         }
22         return -1;
23     }
24 };