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/******************************************************************************
* Compilation: javac DirectedEdge.java
* Execution: java DirectedEdge
* Dependencies: StdOut.java
*
* Immutable weighted directed edge.
*
******************************************************************************/
package edu.princeton.cs.algs4;
/**
* The {@code DirectedEdge} class represents a weighted edge in an
* {@link EdgeWeightedDigraph}. Each edge consists of two integers
* (naming the two vertices) and a real-value weight. The data type
* provides methods for accessing the two endpoints of the directed edge and
* the weight.
*
* For additional documentation, see Section 4.4 of
* Algorithms, 4th Edition by Robert Sedgewick and Kevin Wayne.
*
* @author Robert Sedgewick
* @author Kevin Wayne
*/
public class DirectedEdge {
private final int v;
private final int w;
private final double weight;
/**
* Initializes a directed edge from vertex {@code v} to vertex {@code w} with
* the given {@code weight}.
* @param v the tail vertex
* @param w the head vertex
* @param weight the weight of the directed edge
* @throws IllegalArgumentException if either {@code v} or {@code w}
* is a negative integer
* @throws IllegalArgumentException if {@code weight} is {@code NaN}
*/
public DirectedEdge(int v, int w, double weight) {
if (v < 0) throw new IllegalArgumentException("Vertex names must be nonnegative integers");
if (w < 0) throw new IllegalArgumentException("Vertex names must be nonnegative integers");
if (Double.isNaN(weight)) throw new IllegalArgumentException("Weight is NaN");
this.v = v;
this.w = w;
this.weight = weight;
}
/**
* Returns the tail vertex of the directed edge.
* @return the tail vertex of the directed edge
*/
public int from() {
return v;
}
/**
* Returns the head vertex of the directed edge.
* @return the head vertex of the directed edge
*/
public int to() {
return w;
}
/**
* Returns the weight of the directed edge.
* @return the weight of the directed edge
*/
public double weight() {
return weight;
}
/**
* Returns a string representation of the directed edge.
* @return a string representation of the directed edge
*/
public String toString() {
return v + "->" + w + " " + String.format("%5.2f", weight);
}
/**
* Unit tests the {@code DirectedEdge} data type.
*
* @param args the command-line arguments
*/
public static void main(String[] args) {
DirectedEdge e = new DirectedEdge(12, 34, 5.67);
StdOut.println(e);
}
}
/******************************************************************************
* Copyright 2002-2018, Robert Sedgewick and Kevin Wayne.
*
* This file is part of algs4.jar, which accompanies the textbook
*
* Algorithms, 4th edition by Robert Sedgewick and Kevin Wayne,
* Addison-Wesley Professional, 2011, ISBN 0-321-57351-X.
* http://algs4.cs.princeton.edu
*
*
* algs4.jar is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* algs4.jar is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with algs4.jar. If not, see http://www.gnu.org/licenses.
******************************************************************************/