Graph

All Known Subinterfaces:

UnweightedGraph

All Known Implementing Classes:

MysteryUnweightedGraphImplementation
```
public interface Graph
```
A common interface for the Graph ADT, encompassing graphs both unweighted and weighted, undirected and directed. Note that an object of Graph type can't add edges to itself; the sub-interfaces UnweightedGraph and WeightedGraph contain the necessary methods for adding edges. Note that this particular interface explicitly refers to vertices by a consecutive set of integral vertex IDs, from 0 to N-1 (where N is the number of vertices), and conceives of edges only in terms of their endpoints. This is the canonical conception of a graph for standard graph algorithms, but lacks common features for modeling, e.g., a road network. The user must represent metadata like vertex labels in their own data structures, outside of the graph class itself. Any method that takes one or more vertex IDs as arguments may throw an IndexOutOfBoundsException if any input ID is out of bounds.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`int`	`addVertex()`	Adds a new vertex.
`void`	`clear()`	Removes all vertices and edges from the graph.
`int`	`getDegree(int v)`	Returns the out-degree of the specified vertex.
`int`	`getInDegree(int v)`	Returns the in-degree of the specified vertex.
`java.lang.Iterable<java.lang.Integer>`	`getNeighbors(int v)`	Returns an iterable object that allows iteration over the neighbors of the specified vertex.
`boolean`	`hasEdge(int begin, int end)`	Checks whether an edge exists between two vertices.
`boolean`	`isDirected()`	Returns true if the graph is directed.
`boolean`	`isEmpty()`	Returns true if there are no vertices in the graph.
`int`	`numEdges()`	Returns the number of edges in the graph.
`int`	`numVerts()`	Returns the number of vertices in the graph.

- Method Detail
  - addVertex
```
int addVertex()
```
    Adds a new vertex.
    
    Returns:
    
    the ID of the added vertex.
  - hasEdge
```
boolean hasEdge(int begin,
                int end)
```
    Checks whether an edge exists between two vertices. In an undirected graph, this returns the same as hasEdge(end, begin).
    
    Returns:
    
    true if there is an edge from begin to end.
  - getDegree
```
int getDegree(int v)
```
    Returns the out-degree of the specified vertex.
  - getInDegree
```
int getInDegree(int v)
```
    Returns the in-degree of the specified vertex.
  - getNeighbors
```
java.lang.Iterable<java.lang.Integer> getNeighbors(int v)
```
    Returns an iterable object that allows iteration over the neighbors of the specified vertex. In particular, the vertex u is included in the sequence if and only if there is an edge from v to u in the graph.
  - numVerts
```
int numVerts()
```
    Returns the number of vertices in the graph.
  - numEdges
```
int numEdges()
```
    Returns the number of edges in the graph. The result does *not* double-count edges in undirected graphs.
  - isDirected
```
boolean isDirected()
```
    Returns true if the graph is directed.
  - isEmpty
```
boolean isEmpty()
```
    Returns true if there are no vertices in the graph.
  - clear
```
void clear()
```
    Removes all vertices and edges from the graph.