DepthFirstDirectedPaths (Algorithms 4/e)

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 Θ(V + E) time in the worst case, where V is the number of vertices and E is the number of edges. Each instance method takes Θ(1) time. It uses Θ(V) extra space (not including the digraph).
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 Description

DepthFirstDirectedPaths(Digraph digraph, int s)
Computes a directed path from s to every other vertex in digraph.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	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 java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - DepthFirstDirectedPaths
```
public DepthFirstDirectedPaths(Digraph digraph,
                               int s)
```
    Computes a directed path from s to every other vertex in digraph.
    
    Parameters:
    
    digraph - 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