Package g0801_0900.s0815_bus_routes

Class Solution

java.lang.Object

g0801_0900.s0815_bus_routes.Solution

public class Solution
extends Object

815 - Bus Routes.<p>Hard</p> <p>You are given an array <code>routes</code> representing bus routes where <code>routes[i]</code> is a bus route that the <code>i^th</code> bus repeats forever.</p> <ul> <li>For example, if <code>routes[0] = [1, 5, 7]</code>, this means that the <code>0^th</code> bus travels in the sequence <code>1 -> 5 -> 7 -> 1 -> 5 -> 7 -> 1 -> ...</code> forever.</li> </ul> <p>You will start at the bus stop <code>source</code> (You are not on any bus initially), and you want to go to the bus stop <code>target</code>. You can travel between bus stops by buses only.</p> <p>Return <em>the least number of buses you must take to travel from</em> <code>source</code> <em>to</em> <code>target</code>. Return <code>-1</code> if it is not possible.</p> <p><strong>Example 1:</strong></p> <p><strong>Input:</strong> routes = [[1,2,7],[3,6,7]], source = 1, target = 6</p> <p><strong>Output:</strong> 2</p> <p><strong>Explanation:</strong> The best strategy is take the first bus to the bus stop 7, then take the second bus to the bus stop 6.</p> <p><strong>Example 2:</strong></p> <p><strong>Input:</strong> routes = [[7,12],[4,5,15],[6],[15,19],[9,12,13]], source = 15, target = 12</p> <p><strong>Output:</strong> -1</p> <p><strong>Constraints:</strong></p> <ul> <li><code>1 <= routes.length <= 500</code>.</li> <li><code>1 <= routes[i].length <= 10⁵</code></li> <li>All the values of <code>routes[i]</code> are <strong>unique</strong>.</li> <li><code>sum(routes[i].length) <= 10⁵</code></li> <li><code>0 <= routes[i][j] < 10⁶</code></li> <li><code>0 <= source, target < 10⁶</code></li> </ul>

Constructor Summary

Constructors

Constructor	Description
Solution()

Method Summary

Modifier and Type	Method	Description
int	numBusesToDestination(int[][] routes, int source, int target)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

Solution

public Solution()

Method Details

numBusesToDestination

public int numBusesToDestination(int[][] routes,
 int source,
 int target)