C# || How To Design Underground System To Keep Track Of Customer Travel Times Between Stations Using C#

May 01, 2022 admin No comments

The following is a module with functions which demonstrates how to design an underground system to keep track of customer travel times between different stations using C#.

1. Underground System – Problem Statement

An underground railway system is keeping track of customer travel times between different stations. They are using this data to calculate the average time it takes to travel from one station to another.

Implement the UndergroundSystem class:

void checkIn(int id, string stationName, int t)
- A customer with a card ID equal to id, checks in at the station stationName at time t.
- A customer can only be checked into one place at a time.
void checkOut(int id, string stationName, int t)
- A customer with a card ID equal to id, checks out from the station stationName at time t.
double getAverageTime(string startStation, string endStation)
- Returns the average time it takes to travel from startStation to endStation.
- The average time is computed from all the previous traveling times from startStation to endStation that happened directly, meaning a check in at startStation followed by a check out from endStation.
- The time it takes to travel from startStation to endStation may be different from the time it takes to travel from endStation to startStation.
- There will be at least one customer that has traveled from startStation to endStation before getAverageTime is called.

You may assume all calls to the checkIn and checkOut methods are consistent. If a customer checks in at time t₁ then checks out at time t₂, then t₁ < t₂. All events happen in chronological order.

Example 1:

Input ["UndergroundSystem","checkIn","checkIn","checkIn","checkOut","checkOut","checkOut","getAverageTime","getAverageTime","checkIn","getAverageTime","checkOut","getAverageTime"] [[],[45,"Leyton",3],[32,"Paradise",8],[27,"Leyton",10],[45,"Waterloo",15],[27,"Waterloo",20],[32,"Cambridge",22],["Paradise","Cambridge"],["Leyton","Waterloo"],[10,"Leyton",24],["Leyton","Waterloo"],[10,"Waterloo",38],["Leyton","Waterloo"]]
Output [null,null,null,null,null,null,null,14.00000,11.00000,null,11.00000,null,12.00000]
Explanation UndergroundSystem undergroundSystem = new UndergroundSystem(); undergroundSystem.checkIn(45, "Leyton", 3); undergroundSystem.checkIn(32, "Paradise", 8); undergroundSystem.checkIn(27, "Leyton", 10); undergroundSystem.checkOut(45, "Waterloo", 15); // Customer 45 "Leyton" -> "Waterloo" in 15-3 = 12 undergroundSystem.checkOut(27, "Waterloo", 20); // Customer 27 "Leyton" -> "Waterloo" in 20-10 = 10 undergroundSystem.checkOut(32, "Cambridge", 22); // Customer 32 "Paradise" -> "Cambridge" in 22-8 = 14 undergroundSystem.getAverageTime("Paradise", "Cambridge"); // return 14.00000. One trip "Paradise" -> "Cambridge", (14) / 1 = 14 undergroundSystem.getAverageTime("Leyton", "Waterloo"); // return 11.00000. Two trips "Leyton" -> "Waterloo", (10 + 12) / 2 = 11 undergroundSystem.checkIn(10, "Leyton", 24); undergroundSystem.getAverageTime("Leyton", "Waterloo"); // return 11.00000 undergroundSystem.checkOut(10, "Waterloo", 38); // Customer 10 "Leyton" -> "Waterloo" in 38-24 = 14 undergroundSystem.getAverageTime("Leyton", "Waterloo"); // return 12.00000. Three trips "Leyton" -> "Waterloo", (10 + 12 + 14) / 3 = 12

Example 2:

Input ["UndergroundSystem","checkIn","checkOut","getAverageTime","checkIn","checkOut","getAverageTime","checkIn","checkOut","getAverageTime"] [[],[10,"Leyton",3],[10,"Paradise",8],["Leyton","Paradise"],[5,"Leyton",10],[5,"Paradise",16],["Leyton","Paradise"],[2,"Leyton",21],[2,"Paradise",30],["Leyton","Paradise"]]
Output [null,null,null,5.00000,null,null,5.50000,null,null,6.66667]
Explanation UndergroundSystem undergroundSystem = new UndergroundSystem(); undergroundSystem.checkIn(10, "Leyton", 3); undergroundSystem.checkOut(10, "Paradise", 8); // Customer 10 "Leyton" -> "Paradise" in 8-3 = 5 undergroundSystem.getAverageTime("Leyton", "Paradise"); // return 5.00000, (5) / 1 = 5 undergroundSystem.checkIn(5, "Leyton", 10); undergroundSystem.checkOut(5, "Paradise", 16); // Customer 5 "Leyton" -> "Paradise" in 16-10 = 6 undergroundSystem.getAverageTime("Leyton", "Paradise"); // return 5.50000, (5 + 6) / 2 = 5.5 undergroundSystem.checkIn(2, "Leyton", 21); undergroundSystem.checkOut(2, "Paradise", 30); // Customer 2 "Leyton" -> "Paradise" in 30-21 = 9 undergroundSystem.getAverageTime("Leyton", "Paradise"); // return 6.66667, (5 + 6 + 9) / 3 = 6.66667

2. Underground System – Solution

The following is a solution which demonstrates how to design an underground system to keep track of customer travel times between different stations.





		
		
			2. Underground System - Solution
			
C#
			
			// ============================================================================
//    Author: Kenneth Perkins
//    Date:   May 1, 2022
//    Taken From: http://programmingnotes.org/
//    File:  Solution.cs
//    Description: Demonstrates how to design underground system
// ============================================================================
public class UndergroundSystem {
    Dictionary<string, KeyValuePair<int, int>> checkoutMap;
    Dictionary<int, KeyValuePair<string, int>> checkInMap;

    public UndergroundSystem() {
        checkoutMap = new Dictionary<string, KeyValuePair<int, int>>(); // Route - {TotalTime, Count}
        checkInMap = new Dictionary<int, KeyValuePair<string, int>>();  // Uid - {StationName, Time}
    }

    public void CheckIn(int id, string stationName, int t) {
        checkInMap[id] = new KeyValuePair<string, int>(stationName, t);
    }

    public void CheckOut(int id, string stationName, int t) {
        var checkIn = checkInMap[id];
        var route = checkIn.Key + "_" + stationName;
        var totalTime = t - checkIn.Value;
        var checkout = checkoutMap.ContainsKey(route) ? checkoutMap[route] : new KeyValuePair<int, int>(0, 0);
        checkoutMap[route] = new KeyValuePair<int, int>(checkout.Key + totalTime, checkout.Value + 1);
    }

    public double GetAverageTime(string startStation, string endStation) {
        var route = startStation + "_" + endStation;
        var checkout = checkoutMap[route];
        return (double) checkout.Key / checkout.Value;
    }
}// http://programmingnotes.org/

/**
 * Your UndergroundSystem object will be instantiated and called as such:
 * UndergroundSystem obj = new UndergroundSystem();
 * obj.CheckIn(id,stationName,t);
 * obj.CheckOut(id,stationName,t);
 * double param_3 = obj.GetAverageTime(startStation,endStation);
 */
			
				
					
				
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						// ============================================================================
//    Author: Kenneth Perkins
//    Date:   May 1, 2022
//    Taken From: http://programmingnotes.org/
//    File:  Solution.cs
//    Description: Demonstrates how to design underground system
// ============================================================================
public class UndergroundSystem {
    Dictionary<string, KeyValuePair<int, int>> checkoutMap;
    Dictionary<int, KeyValuePair<string, int>> checkInMap;
 
    public UndergroundSystem() {
        checkoutMap = new Dictionary<string, KeyValuePair<int, int>>(); // Route - {TotalTime, Count}
        checkInMap = new Dictionary<int, KeyValuePair<string, int>>();  // Uid - {StationName, Time}
    }
 
    public void CheckIn(int id, string stationName, int t) {
        checkInMap[id] = new KeyValuePair<string, int>(stationName, t);
    }
 
    public void CheckOut(int id, string stationName, int t) {
        var checkIn = checkInMap[id];
        var route = checkIn.Key + "_" + stationName;
        var totalTime = t - checkIn.Value;
        var checkout = checkoutMap.ContainsKey(route) ? checkoutMap[route] : new KeyValuePair<int, int>(0, 0);
        checkoutMap[route] = new KeyValuePair<int, int>(checkout.Key + totalTime, checkout.Value + 1);
    }
 
    public double GetAverageTime(string startStation, string endStation) {
        var route = startStation + "_" + endStation;
        var checkout = checkoutMap[route];
        return (double) checkout.Key / checkout.Value;
    }
}// http://programmingnotes.org/
 
/**
 * Your UndergroundSystem object will be instantiated and called as such:
 * UndergroundSystem obj = new UndergroundSystem();
 * obj.CheckIn(id,stationName,t);
 * obj.CheckOut(id,stationName,t);
 * double param_3 = obj.GetAverageTime(startStation,endStation);
 */

QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

Once compiled, you should get this as your output for the example cases:

[null,null,null,null,null,null,null,14.00000,11.00000,null,11.00000,null,12.00000] [null,null,null,5.00000,null,null,5.50000,null,null,6.66667]

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Posted in: C#, Console Tags: c-sharp, leetcode

C# || How To Design Underground System To Keep Track Of Customer Travel Times Between Stations Using C#

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