33. Search in Rotated Sorted Array

题目描述：

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]).

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.

Your algorithm's runtime complexity must be in the order of O(log n).

Example 1:

Input: nums = [4,5,6,7,0,1,2], target = 0
Output: 4

Example 2:

Input: nums = [4,5,6,7,0,1,2], target = 3
Output: -1

程序：

class Solution {
public:
    int search(vector& nums, int target) {
        if(nums.size() == 0) return -1;
        if(nums.size() == 1 && nums[0] == target) return 0;
        int i = 0, j = nums.size()-1;
        while(i < j){
            if(nums[i] < target) i++;
            if(nums[j] > target) j--;
            if(nums[i] == target) return i;
            if(nums[j] == target) return j;
            if(nums[i] > target && nums[j] < target) return -1;
        }
        return -1;
    }
};