Distance Between Bus Stops - Array - Easy - LeetCode

A bus has n stops numbered from 0 to n - 1 that form a circle. We know the distance between all pairs of neighboring stops where distance[i] is the distance between the stops number i and (i + 1) % n.

The bus goes along both directions i.e. clockwise and counterclockwise.

Return the shortest distance between the given start and destination stops.

Example 1:

Input: distance = [1,2,3,4], start = 0, destination = 1

Output: 1

Explanation: Distance between 0 and 1 is 1 or 9, minimum is 1.

Example 2:

Input: distance = [1,2,3,4], start = 0, destination = 2

Output: 3

Explanation: Distance between 0 and 2 is 3 or 7, minimum is 3.

Example 3:

Input: distance = [1,2,3,4], start = 0, destination = 3

Output: 4

Explanation: Distance between 0 and 3 is 6 or 4, the minimum is 4.

Constraints:

1 <= n <= 10^4

distance.length == n

0 <= start, destination < n

0 <= distance[i] <= 10^4

Solution:

using System;
using System.Collections.Generic;
using System.Text;

namespace LeetCode.AskGif.Easy.Array
{
 public class DistanceBetweenBusStopsSoln
 {
 public int DistanceBetweenBusStops(int[] distance, int start, int destination)
 { 
 var clockwise = 0;
 bool clockwiseFound = false;

 var antiClockwise = 0;
 bool antiClockwiseFound = false;
 int i = start;
 int j = start;
 
 while (true)
 {
 i++;
 j--;

 if (i > distance.Length - 1)
 {
 i = 0;
 }

 if (j < 0)
 {
 j = distance.Length - 1;
 }

 if (i == destination)
 {
 if ((i - 1) < 0)
 {
 clockwise += distance[distance.Length - 1];
 }
 else
 {
 clockwise += distance[i - 1];
 } 
 clockwiseFound = true;
 }

 if( j == destination)
 { 
 antiClockwise += distance[j]; 
 antiClockwiseFound = true;
 }

 if (!clockwiseFound)
 {
 if ((i - 1) < 0)
 {
 clockwise += distance[distance.Length - 1];
 }
 else
 {
 clockwise += distance[i - 1];
 }
 }

 if (!antiClockwiseFound)
 { 
 antiClockwise += distance[j]; 
 } 
 
 if(clockwiseFound && antiClockwiseFound)
 {
 break;
 }
 }

 return clockwise < antiClockwise ? clockwise : antiClockwise;
 }
 }
}

Time Complexity: O(n)

Space Complexity: O(1)

Unit Tests:

using LeetCode.AskGif.Easy.Array;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using System;
using System.Collections.Generic;
using System.Text;

namespace CodingUnitTest.Easy.Array
{
 [TestClass]
 public class DistanceBetweenBusStopsSolnTests
 {
 [TestMethod]
 public void DistanceBetweenBusStopsSoln_First()
 {
 var distance = new int[] { 1, 2, 3, 4 };
 var start = 0;
 var destination = 1;

 var output = 1;

 var res = new DistanceBetweenBusStopsSoln().DistanceBetweenBusStops(distance, start, destination);

 Assert.AreEqual(output, res);
 }

 [TestMethod]
 public void DistanceBetweenBusStopsSoln_Second()
 {
 var distance = new int[] { 1, 2, 3, 4 };
 var start = 0;
 var destination = 2;

 var output = 3;

 var res = new DistanceBetweenBusStopsSoln().DistanceBetweenBusStops(distance, start, destination);

 Assert.AreEqual(output, res);
 }

 [TestMethod]
 public void DistanceBetweenBusStopsSoln_Third()
 {
 var distance = new int[] { 1, 2, 3, 4 };
 var start = 0;
 var destination = 3;

 var output = 4;

 var res = new DistanceBetweenBusStopsSoln().DistanceBetweenBusStops(distance, start, destination);

 Assert.AreEqual(output, res);
 }

 [TestMethod]
 public void DistanceBetweenBusStopsSoln_Fourt()
 { 
 var distance = new int[] { 7, 10, 1, 12, 11, 14, 5, 0 };
 var start = 7;
 var destination = 2;

 var output = 17;

 var res = new DistanceBetweenBusStopsSoln().DistanceBetweenBusStops(distance, start, destination);

 Assert.AreEqual(output, res);
 }

 [TestMethod]
 public void DistanceBetweenBusStopsSoln_Fifth()
 { 
 var distance = new int[] { 3, 6, 7, 2, 9, 10, 7, 16, 11 };
 var start = 6;
 var destination = 2;

 var output = 28;

 var res = new DistanceBetweenBusStopsSoln().DistanceBetweenBusStops(distance, start, destination);

 Assert.AreEqual(output, res);
 }

 [TestMethod]
 public void DistanceBetweenBusStopsSoln_Sixth()
 { 
 var distance = new int[] { 14, 13, 4, 7, 10, 17, 8, 3, 2, 13 };
 var start = 2;
 var destination = 9;

 var output = 40;

 var res = new DistanceBetweenBusStopsSoln().DistanceBetweenBusStops(distance, start, destination);

 Assert.AreEqual(output, res);
 }
 }
}