LeetCode:34. 在排序数组中查找元素的第一个和最后一个位置

class Solution {
public:

    int search(vector<int>& nums, int target){
        int left=0;
        int right=nums.size()-1;
        while(left<=right)
        {
            if(target==nums[(left+right)/2])
            {
                return (left+right)/2;
            }
            else if(target>nums[(left+right)/2])
            {
                left=(left+right)/2+1;
            }
            else
            {
                right=(left+right)/2-1;
            }
        }
        return -1;
    }

    vector<int> searchRange(vector<int>& nums, int target) {
        int pos=search(nums,target);
        vector<int>res;
        if(pos==-1)
        {
            res.push_back(-1);
            res.push_back(-1);
            return res;
        }
        int left=pos;
        int right=pos;
        while(left>=0&&nums[left]==target)
        {
            left--;
        }
        left++;
        while(right<nums.size()&&nums[right]==target)
        {
            right++;
        }
        right--;
        res.push_back(left);
        res.push_back(right);
        return res;
    }
};