leetcode33~Search 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).
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.

难点在于边界的确定，自己假设一个数组，把各种可能情况比对一下

public class SearchinRotatedSortedArray {    public int search(int[] nums, int target) {        if(nums.length==0 || nums==null) return -1;        int start=0,end=nums.length-1;        while(start<=end) {            int mid = start+(end-start)/2;            if(nums[mid]==target) return mid;            //这里必须是<= 案例{3,1} 1            if(nums[start]<=nums[mid]) {                if(nums[start]<=target && target<nums[mid]) { //左边查找                    end = mid-1;                } else {                    start = mid+1;                }            } else {                if(nums[mid]<target && target<=nums[end]) {  //右边查找                    start = mid+1;                } else {                    end = mid-1;                }            }        }        return -1;    }}