LOJ 1069 - Lift

Problem: You are given what floor you are on and what floor the lift is on. You need to calculate how many seconds you will need to get to ground floor.

Assume that it takes 4 seconds for the lift to go from any floor to its adjacent floor (up or down). It takes 3 seconds to open or close the door of the lift and you need 5 seconds to enter or exit the lift.

That means you need to calculate the total time, T = time needed by the lift to come to your floor + time needed by the lift door to open + time needed by you to enter the lift + time needed by the lift door to close + time needed by the lift to reach ground floor + time needed by the lift door to open again + time needed by you to exit the lift.

Here,

• time needed by the lift to come to your floor = abs(myPosition-liftPosition) * 4sec

• time needed by the lift door to open = 3sec

• time needed by you to enter the lift = 5sec

• time needed by lift door to close = 3sec

• time needed by the lift to reach ground floor = myPosition * 4sec

• time needed by the lift door to open again = 3sec

• time needed by you to exit the lift = 5sec

C++

#include<bits/stdc++.h>
using namespace std;

int main(){
    int testcase; 
    cin>>testcase;

    for(int t=1; t<=testcase; t++){
        int myPosition, liftPosition;
        cin>>myPosition>>liftPosition;

        int timeTakenByMeToEnter= 5;
        int timeTakenByMeToExit= 5;
        int timeTakenByLiftToOpen= 3;
        int timeTakenByLiftToClose= 3;
        int timeTakenByLiftToReachMyFloor= abs(myPosition-liftPosition)*4; // If lift was on floor 7 and I was on floor 2, number of floors passed by the lift would be (2-7)=-5. But number of floors cannot be negative. To avoid the minus sign, we used the abs() function. As the lift takes 4 seconds to reach the adjacent floor, we multiply by 4.
        int timeTakenByLiftToReachGroundFloorFromMyFloor= (myPosition)*4; // Lift takes 4 seconds to go from one floor to the next floor. That's why we multiply by 4.

        int ans = timeTakenByLiftToReachMyFloor + timeTakenByLiftToOpen + timeTakenByMeToEnter + timeTakenByLiftToClose + timeTakenByLiftToReachGroundFloorFromMyFloor + timeTakenByLiftToOpen + timeTakenByMeToExit;

        cout<<"Case "<<t<<": "<< ans <<endl;
    }
}

Java

package com.loj.volume;

import java.util.Scanner;

class Lift {
  public static void main(String[] args) throws Exception {
    Scanner scanner = new Scanner(System.in);
    int cases = scanner.nextInt();
    for (int caseno = 1; caseno <= cases; ++caseno) {
      int myPosition = scanner.nextInt();
      int liftPosition = scanner.nextInt();

      int timeTakenByMeToEnter= 5;
      int timeTakenByMeToExit= 5;
      int timeTakenByLiftToOpen= 3;
      int timeTakenByLiftToClose= 3;
      int timeTakenByLiftToReachMyFloor= Math.abs(myPosition-liftPosition)*4; // If lift was on floor 7 and I was on floor 2, number of floors passed by the lift would be (2-7)=-5. But number of floors cannot be negative. To avoid the minus sign, we used the abs() function. As the lift takes 4 seconds to reach the adjacent floor, we multiply by 4.
      int timeTakenByLiftToReachGroundFloorFromMyFloor= (myPosition)*4; // Lift takes 4 seconds to go from one floor to the next floor. That's why we multiply by 4.

      int ans = timeTakenByLiftToReachMyFloor + timeTakenByLiftToOpen + timeTakenByMeToEnter + timeTakenByLiftToClose + timeTakenByLiftToReachGroundFloorFromMyFloor + timeTakenByLiftToOpen + timeTakenByMeToExit;

      System.out.println("Case " + caseno + ": " + ans);
    }
  }
}

Happy Coding!

Written by: Md. Arfaqur Rahman

Tutorial source