leetcode Search in Rotated Sorted Array II

每次二分有四种情况：

1. nums[mid] = target，则可以返回mid

2. nums[mid] < nums[right]，说明在[mid, right]区间是右边递增的区间，然后判断target是否在这个区间内

    1）如果nums[mid] < target <= nums[right]，说明target在右边区间里，则left = mid + 1;

    2）否则在左边区间里，搜索左边区间，right = mid - 1;

3. nums[mid] > nums[right]，说明[elft, mid]区间是在左边的递增区间，然后判断target是否在这个左边区间里

    1）如果nums[left] <= target < nums[mid]，说明target在这个区间里，则使right = mid - 1;

    2）否则说明target在[mid, right]的不规则区间里，搜索右边区间，则使left = mid + 1;

4. nums[mid] == nums[right]，这种情况并不知道搜索哪一边，因为nums[right] != target，此时可以抛弃nums[right]，搜索[left, right-1]的区域

 

 

 

class Solution {
public:
    bool searchD(vector<int> & nums, int target, int s, int e)
    {

        cout<<s<<"  "<<e<<endl;
        if(s>e||(s==e&& nums[s]!=target))
            return false;
        
        int mid=s+(e-s)/2;
        if(target==nums[mid])
            return true;
        
      //  cout<<s<<"  "<<e<<"  "<<mid<<endl;
      //  cout<<nums[mid]<<"  "<<nums[s]<<"   "<<nums[e]<<endl;
        if(nums[s]==target)
            return true;
        if(nums[e]==target)
            return true;
        if(nums[mid]==nums[s]&& nums[mid==nums[e]])
            return searchD(nums, target, s+1,e-1);
        if(nums[mid]>nums[e])
        {
           
            if(nums[mid]>target&&nums[s]<target )
            { 
             //   cout<<'1'<<endl;
                return searchD(nums, target,s, mid);
            }
                
                
            else
            {
             //   cout<<'2'<<endl;
                 return searchD(nums,target, mid+1,e);
            }
               
        }
        else
        {
            if(nums[mid]<target&& target<nums[e])
            {
             //   cout<<'3'<<endl;
                return searchD(nums,target,mid+1, e);
            }
                
            else
            {
              //  cout<<'4'<<endl;
                return searchD(nums,target,s, mid);
            }
                
        }
            
            
    }
    bool search(vector<int>& nums, int target) {
        int size=nums.size();
        if(size<1)
            return false;
        bool result=searchD(nums, target, 0, size-1);
        return result;
    }
};