GFG Aggressive Cows

class Solution {
public:

    int solve(int n, int k, vector<int> &stalls) {
       sort(stalls.begin(),stalls.end());
       int l=0;
       int h=stalls[n-1];
       int ans=-1;
       while(l<=h)
       {
           int mid=l+(h-l)/2;
           if(isPossible(mid,stalls,k))
           {
               ans=mid;
               l=mid+1;
           }
           else
           {
               h=mid-1;
           }
       }
       return ans;
    }
    bool isPossible(int mid,vector<int> &stalls,int k)
    {
        int last=0;
        int count=1;
        int n=stalls.size();
        
         while(last<n)
        {
            auto lower=lower_bound(stalls.begin()+last,stalls.end(),stalls[last]+mid);
            if(lower!=stalls.end())
            {
            int pos=lower-stalls.begin();
            last=pos;
            if(last>=n)
            break;
            ++count;
            }
            else
            break;
            
        }
        
        /*int n=stalls.size();
        int l=0;
        int h=n-1;
        while(last<n)
        {
            l=last+1;
            h=n-1;
            int t=-1;
            while(l<=h){
            int m=l+(h-l)/2;
            if(stalls[m]-stalls[last]>=mid)
            {
                t=m;
                h=m-1;
            }
            else
            {
                l=m+1;
            }
            }
            if(t!=-1)
            last=t;
            else
            break;
            ++count;
        }*/
        
        
        if(count>=k)
        return true;
        else
        return false;
    }
};