edu.princeton.cs.algs4

## Class DepthFirstDirectedPaths

• Object
• edu.princeton.cs.algs4.DepthFirstDirectedPaths

• ```public class DepthFirstDirectedPaths
extends Object```
The `DepthFirstDirectedPaths` class represents a data type for finding directed paths from a source vertex s to every other vertex in the digraph.

This implementation uses depth-first search. The constructor takes time proportional to V + E, where V is the number of vertices and E is the number of edges. It uses extra space (not including the graph) proportional to V.

For additional documentation, see Section 4.2 of Algorithms, 4th Edition by Robert Sedgewick and Kevin Wayne.

Author:
Robert Sedgewick, Kevin Wayne
• ### Constructor Summary

Constructors
Constructor and Description
```DepthFirstDirectedPaths(Digraph G, int s)```
Computes a directed path from `s` to every other vertex in digraph `G`.
• ### Method Summary

Methods
Modifier and Type Method and Description
`boolean` `hasPathTo(int v)`
Is there a directed path from the source vertex `s` to vertex `v`?
`static void` `main(String[] args)`
Unit tests the `DepthFirstDirectedPaths` data type.
`Iterable<Integer>` `pathTo(int v)`
Returns a directed path from the source vertex `s` to vertex `v`, or `null` if no such path.
• ### Methods inherited from class Object

`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`
• ### Constructor Detail

• #### DepthFirstDirectedPaths

```public DepthFirstDirectedPaths(Digraph G,
int s)```
Computes a directed path from `s` to every other vertex in digraph `G`.
Parameters:
`G` - the digraph
`s` - the source vertex
Throws:
`IllegalArgumentException` - unless `0 <= s < V`
• ### Method Detail

• #### hasPathTo

`public boolean hasPathTo(int v)`
Is there a directed path from the source vertex `s` to vertex `v`?
Parameters:
`v` - the vertex
Returns:
`true` if there is a directed path from the source vertex `s` to vertex `v`, `false` otherwise
Throws:
`IllegalArgumentException` - unless `0 <= v < V`
• #### pathTo

`public Iterable<Integer> pathTo(int v)`
Returns a directed path from the source vertex `s` to vertex `v`, or `null` if no such path.
Parameters:
`v` - the vertex
Returns:
the sequence of vertices on a directed path from the source vertex `s` to vertex `v`, as an Iterable
Throws:
`IllegalArgumentException` - unless `0 <= v < V`
• #### main

`public static void main(String[] args)`
Unit tests the `DepthFirstDirectedPaths` data type.
Parameters:
`args` - the command-line arguments