Leetcode81. 搜索旋转排序数组 II

class Solution {
public:
    bool check(vector<int> &nums,int target,int l,int r)//[l,r]区间查找target
    {
        while(l<r)
        {
            int mid=(l+r+1)>>1;
            if(target>=nums[mid])   l=mid;
            else r=mid-1;
        }
        return nums[l]==target;
    }
    bool search(vector<int>& nums, int target) {
        int n=nums.size()-1;
        while(n&&nums[n]==nums[0])  n--;
        if(nums[n]>nums[0]) //说明只有一段单调的
            return check(nums,target,0,n);
        int l=0,r=n;
        while(l<r)
        {
            int mid=(l+r)>>1;
            if(nums[mid]>=nums[0])   l=mid+1;
            else r=mid;
        }
        //根据target与nums[0]的关系，判断二分区间
        if(target>=nums[0])  return check(nums,target,0,l-1);
        else return check(nums,target,l,n);
    }
};