Search for a Range

class Solution {
public:
    vector<int> searchRange(vector<int>& nums, int target) {
        int len=nums.size();
        int l=0,r=len-1;
        int mid;
        vector<int>res;
        int flag=0;
        while(l<=r)
        {
            mid=l+(r-l)/2;
            if(nums[mid]<target)
                l=mid+1;
            else if(nums[mid]>target)
                r=mid-1;
            else
            {
                flag=1;
                break;
            }
        }
        if(flag==0)
        {
             res.push_back(-1);
             res.push_back(-1);
        }
        else
        {
            l=mid;
            r=mid;
            while(l>=0&&nums[l]==target)
            {
                if(nums[l]==target)
                l--;
            }
            while(r<=len-1&&nums[r]==target)
            {
                if(nums[r]==target)
                r++;
            }
            
             res.push_back(l+1);
             res.push_back(r-1);
        }
       return res;    
    }
};