https://leetcode.com/problems/search-in-rotated-sorted-array-ii/

解题思路：思路就是一个变形的二分查找，只不过要先找到中间降序的那个点，如果存在则分左右两边分别二分查找，如果不存在降序点，则直接二分查找

class Solution {
    public boolean search(int[] nums, int target) {
        if(nums.length == 0)return false;
        int pos = -1;
        for(int i=0;i<nums.length-1;i++){
            if(nums[i]>nums[i+1]){
                pos = i;
            }
        }
       int n = target;
       return  pos == -1?find(nums,0,nums.length-1,n): (find(nums,0,pos,n)||find(nums,pos+1,nums.length-1,n));
    }
    
    //经典二分查找程序
    private boolean find(int[] nums,int start,int end,int n){
        if(start >end)return false;
        
        while(start <= end){
            int mid = start +(end - start)/2;
            if( n == nums[mid] )return true;
            if(n < nums[mid]){
                end = mid-1 ;
            }else if(n >nums[mid]){
                start = mid+1;
            }
        }
        return false;
    }
}