package edu.princeton.cs.algs4.ch43;
import edu.princeton.cs.introcs.*;
/*************************************************************************
* Compilation: javac Edge.java
* Execution: java Edge
*
* Immutable weighted edge.
*
*************************************************************************/
/**
* The <tt>Edge</tt> class represents a weighted edge in an
* {@link EdgeWeightedGraph}. 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 edge and
* the weight. The natural order for this data type is by
* ascending order of weight.
* <p>
* For additional documentation, see <a href="http://algs4.cs.princeton.edu/43mst">Section 4.3</a> of
* <i>Algorithms, 4th Edition</i> by Robert Sedgewick and Kevin Wayne.
*
* @author Robert Sedgewick
* @author Kevin Wayne
*/
public class Edge implements Comparable<Edge> {
private final int v;
private final int w;
private final double weight;
/**
* Initializes an edge between vertices <tt>v/tt> and <tt>w</tt> of
* the given <tt>weight</tt>.
* param v one vertex
* param w the other vertex
* param weight the weight of the edge
* @throws IndexOutOfBoundsException if either <tt>v</tt> or <tt>w</tt>
* is a negative integer
* @throws IllegalArgumentException if <tt>weight</tt> is <tt>NaN</tt>
*/
public Edge(int v, int w, double weight) {
if (v < 0) throw new IndexOutOfBoundsException("Vertex name must be a nonnegative integer");
if (w < 0) throw new IndexOutOfBoundsException("Vertex name must be a nonnegative integer");
if (Double.isNaN(weight)) throw new IllegalArgumentException("Weight is NaN");
this.v = v;
this.w = w;
this.weight = weight;
}
/**
* Returns the weight of the edge.
* @return the weight of the edge
*/
public double weight() {
return weight;
}
/**
* Returns either endpoint of the edge.
* @return either endpoint of the edge
*/
public int either() {
return v;
}
/**
* Returns the endpoint of the edge that is different from the given vertex
* (unless the edge represents a self-loop in which case it returns the same vertex).
* @param vertex one endpoint of the edge
* @return the endpoint of the edge that is different from the given vertex
* (unless the edge represents a self-loop in which case it returns the same vertex)
* @throws java.lang.IllegalArgumentException if the vertex is not one of the endpoints
* of the edge
*/
public int other(int vertex) {
if (vertex == v) return w;
else if (vertex == w) return v;
else throw new IllegalArgumentException("Illegal endpoint");
}
/**
* Compares two edges by weight.
* @param that the other edge
* @return a negative integer, zero, or positive integer depending on whether
* this edge is less than, equal to, or greater than that edge
*/
public int compareTo(Edge that) {
if (this.weight() < that.weight()) return -1;
else if (this.weight() > that.weight()) return +1;
else return 0;
}
/**
* Returns a string representation of the edge.
* @return a string representation of the edge
*/
public String toString() {
return String.format("%d-%d %.5f", v, w, weight);
}
/**
* Unit tests the <tt>Edge</tt> data type.
*/
public static void main(String[] args) {
Edge e = new Edge(12, 23, 3.14);
StdOut.println(e);
}
}
/*************************************************************************
* Copyright 2002-2012, Robert Sedgewick and Kevin Wayne.
*
* This file is part of algs4-package.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-package.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-package.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-package.jar. If not, see http://www.gnu.org/licenses.
*************************************************************************/