search for a range

leetcode-search_range

class Solution {
public:
    vector<int> searchRange(int A[], int n, int target) {
        vector<int> ret;
        int point=binarySearch(A,0,n-1,target);
        if(point==-1){
            ret.push_back(-1);
            ret.push_back(-1);
            return ret;
        }
        
        while(point>=0){
            if(A[point]==target){
                point--;
                continue;
            }
            else
                break;
        }
        int first=++point;
        
        while(point<=n-1){
            if(A[point]==target){
                point++;
                continue;
            }
            else
                break;
        }
        int last=--point;
        
        ret.push_back(first);
        ret.push_back(last);
        return ret;
    }
    
	int binarySearch(int A[], int left, int right, int target){
		int middle=left+(right-left)/2;
		if(left>right)
			return -1;
		else{
			if(A[middle]==target)
				return middle;
			else if(target>A[middle])
				return binarySearch(A,middle+1,right,target);
			else
				return binarySearch(A,left,middle-1,target);
		}
	}
};

line 38行的二分查找应该像这样求中值，然后判断的条件也改为left>right。 此题主要是在考察二分查找，其余的考点为附带。