グラフ－隣接行列表示

public class AdjacencyWDigraph extends Graph {
	int n; // number of vertices
	int e; // number of edges
	Object[][] a; // adjacency array

	public AdjacencyWDigraph(int theVertices) {
		if (theVertices < 0)
			throw new IllegalArgumentException(
					"number of vertices must be >= 0");
		n = theVertices;
		a = new Object[n + 1][n + 1];
	}

	public AdjacencyWDigraph() {
		this(0);
	}

	public int vertices() {
		return n;
	}

	public int edges() {
		return e;
	}

	public boolean existsEdge(int i, int j) {
		if (i < 1 || j < 1 || i > n || j > n || a[i][j] == null)
			return false;
		else
			return true;
	}

	public void putEdge(Object theEdge) {
		WeightedEdge edge = (WeightedEdge) theEdge;
		int v1 = edge.vertex1;
		int v2 = edge.vertex2;
		if (v1 < 1 || v2 < 1 || v1 > n || v2 > n || v1 == v2)
			throw new IllegalArgumentException("(" + v1 + "," + v2
					+ ") is not a permissible edge");
		if (a[v1][v2] == null) // new edge
			e++;
		a[v1][v2] = edge.weight;
	}

	public void removeEdge(int i, int j) {
		if (i >= 1 && j >= 1 && i <= n && j <= n && a[i][j] != null) {
			a[i][j] = null;
			e--;
		}
	}

	public int degree(int i) {
		throw new NoSuchMethodError();
	}

	public int outDegree(int i) {
		if (i < 1 || i > n)
			throw new IllegalArgumentException("no vertex " + i);
		int sum = 0;
		for (int j = 1; j <= n; j++)
			if (a[i][j] != null)
				sum++;
		return sum;
	}

	public int inDegree(int i) {
		if (i < 1 || i > n)
			throw new IllegalArgumentException("no vertex " + i);
		int sum = 0;
		for (int j = 1; j <= n; j++)
			if (a[j][i] != null)
				sum++;
		return sum;
	}

	public void output() {
		for (int i = 1; i <= n; i++) {
			for (int j = 1; j <= n; j++)
				System.out.print(a[i][j] + " ");
			System.out.println();
		}
	}

	public Iterator iterator(int i) {
		if (i < 1 || i > n)
			throw new IllegalArgumentException("no vertex " + i);
		return new VertexIterator(i);
	}

	private class VertexIterator implements Iterator {
		private int v; // the vertex being iterated
		private int nextVertex;

		public VertexIterator(int i) {
			v = i;
			for (int j = 1; j <= n; j++)
				if (a[v][j] != null) {
					nextVertex = j;
					return;
				}
			nextVertex = n + 1;
		}

		public boolean hasNext() {
			return nextVertex <= n;
		}

		public Object next() {
			if (nextVertex <= n) {
				int u = nextVertex;
				for (int j = u + 1; j <= n; j++)
					if (a[v][j] != null) {
						nextVertex = j;
						return new WeightedEdgeNode(u, a[v][u]);
					}

				// no next adjacent vertex for v
				nextVertex = n + 1;
				return new WeightedEdgeNode(u, a[v][u]);
			} else
				throw new NoSuchElementException("no next vertex");
		}

		/** unsupported method */
		public void remove() {
			throw new UnsupportedOperationException();
		}
	}
}

public class AdjacencyWGraph extends AdjacencyWDigraph {
	public AdjacencyWGraph(int theVertices) {
		super(theVertices);
	}

	public AdjacencyWGraph() {
		this(0);
	}

	public void putEdge(Object theEdge) {
		WeightedEdge edge = (WeightedEdge) theEdge;
		int v1 = edge.vertex1;
		int v2 = edge.vertex2;
		if (v1 < 1 || v2 < 1 || v1 > n || v2 > n || v1 == v2)
			throw new IllegalArgumentException("(" + v1 + "," + v2
					+ ") is not a permissible edge");

		if (a[v1][v2] == null) // new edge
			e++;
		a[v1][v2] = edge.weight;
		a[v2][v1] = edge.weight;
	}

	public void removeEdge(int i, int j) {
		if (i >= 1 && j >= 1 && i <= n && j <= n && a[i][j] != null) {
			a[i][j] = null;
			a[j][i] = null;
			e--;
		}
	}

	public int degree(int i) {
		if (i < 1 || i > n)
			throw new IllegalArgumentException("no vertex " + i);
		int sum = 0;
		for (int j = 1; j <= n; j++)
			if (a[i][j] != null)
				sum++;

		return sum;
	}

	public int outDegree(int i) {
		return degree(i);
	}

	public int inDegree(int i) {
		return degree(i);
	}
}