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.
这道题可以和之前那个rotated sorted array的思路一样,cut haof of array every time来找target。
然后就没啥可说了,单独写一个find()method比较方便。
只是要注意这里的if的条件就要细致的多了,要多考虑,最好画个图(……我就画了,因为浆糊了不画图哈哈哈)
代码如下。~
public class Solution { public int search(int[] nums, int target) { int len=nums.length; return find(nums,0,len-1,target); } public int find(int[] nums,int start,int end,int target){ if(start>end){ return -1; } int mid=(start+end)/2; if(nums[mid]==target){ return mid; } if((target<nums[mid]&&target>=nums[start])||(target<nums[mid]&&nums[mid]<nums[start])||(target>=nums[start]&&nums[start]>nums[mid])){ return find(nums,start,mid-1,target); } return find(nums,mid+1,end,target); } }