Location of dichotomy

A daily topic ing, Today is a day medium topic 34. Find First and Last Position of Element in Sorted Array

class Solution {
    
public:
    vector<int> searchRange(vector<int>& nums, int target) {
    
        int l=0,r=nums.size()-1,mid=0;
        while(l<=r){
    
            mid=(l+r)/2;
            if(target>=nums[mid]){
    
                l=mid+1;
            }
            else if(target<nums[mid]){
    
                r=mid-1;
            }
        }
        vector<int> ret(2,-1);
        if(r==-1||nums[r]!=target){
    
            return ret;
        }
        int i=r;
        while(i>=0&&nums[i]==target){
    
            i--;
        }
        ret[0]=i+1;
        int j=r;
        while(j<=nums.size()-1&&nums[j]==target){
    
            j++;
        }
        ret[1]=j-1;
        return ret;
    }
};