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  1. Practice
  2. Data Structures
  3. Queues
  4. Truck Tour
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Truck Tour

  • driftwood + 1 comment

    C++ USERS

    This problem can be completed in O(N) (linear) time complexity using std::queue<type>; if you've not utilized queue when solving the problem, you've not been successful (mind the category that the problem is in...)

    HINTS:

    • - You require only the standard constructor class of std::queue<type>

    • - O(N) is possible; you must only iterate through the queue<type> once

    • - Mind the size of input variables; set type accordingly

    • - queue<type>'s type must make use of std::pair<type,type>

    • GrahamS + 1 comment

      I used a <vector> rather than a <queue>, and then just wrapped the index around to make it a circular queue. Still a "queue-based solution" but a bit more efficient than repeatedly pushing and popping elements.

      struct Pump {
    int fuel;
    int distanceToNext;
    Pump(int f,int d) : fuel(f), distanceToNext(d) {}
};

bool getTruckin (vector<Pump>& pumps, int startPump) {
    int fuelInTank = 0;
    int currentPump = startPump;
    
    while (true) {
        fuelInTank += pumps[currentPump].fuel; // Fill her up
        
        if (fuelInTank < pumps[currentPump].distanceToNext) {
            // Not enough fuel to reach next pump
            return false; 
        } else {
            int nextPump = (currentPump + 1) % pumps.size();
            if (nextPump == startPump) {
                return true; // Completed loop
            } else {
                fuelInTank -= pumps[currentPump].distanceToNext;
                currentPump = nextPump; // Keep on truckin
            }
        }
    }
}
      • jyotsanamall12 + 0 comments

        hey i used queues too...but i am getting a wrong answer for test cases in which n= 100000. where is this code going wrong. please help!

        void queue :: circle()
{
    node *now= front;
    int Pleft= 0, c= 0, index= 0;
    node *temp= now, *ptr= now;
    while(temp->next != now)
    {
        
        Pleft+= temp->petrol;
        //cout<<"pleft: "<<Pleft<<" distance: "<<temp->dist<<endl;
        if(Pleft < temp->dist)
        {
            temp= ptr->next;
            now= temp;
            ptr= temp;
            Pleft= 0;
            c= 0;
        }
        else
        {
            c++;
            if(c == 1)
            {
                ptr= temp;
                index= temp->petrol;
            }   
            Pleft-= temp->dist;
           // cout<<"in else pleft: "<<Pleft<<endl;
            temp= temp->next;
        }
    }
    int flag= 0;
    while(front->next != front)
    {
        if(index == front->petrol)
        {
            cout<<flag<<endl;
            break;
        }
        flag++;
        front= front->next;
    }
}