91 lines
2.7 KiB
Java
91 lines
2.7 KiB
Java
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import edu.princeton.cs.introcs.StdOut;
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/*************************************************************************
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* Compilation: javac DirectedEdge.java
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* Execution: java DirectedEdge
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*
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* Immutable weighted directed edge.
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*
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*************************************************************************/
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/**
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* The DirectedEdge class represents a weighted edge in an
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* {@link EdgeWeightedDigraph}. Each edge consists of two integers
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* (naming the two vertices) and a real-value weight. The data type
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* provides methods for accessing the two endpoints of the directed edge and
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* the weight.
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*
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* For additional documentation, see <a href="http://algs4.cs.princeton.edu/44sp">Section 4.4</a> of
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* Algorithms, 4th Edition by Robert Sedgewick and Kevin Wayne.
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*
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* @author Robert Sedgewick
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* @author Kevin Wayne
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*/
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public class DirectedEdge {
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private final int v;
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private final int w;
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private final double weight;
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/**
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* Initializes a directed edge from vertex v to vertex w with
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* the given weight .
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* @param v the tail vertex
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* @param w the head vertex
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* @param weight the weight of the directed edge
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* @throws java.lang.IndexOutOfBoundsException if either v or w
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* is a negative integer
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* @throws IllegalArgumentException if weight is NaN
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*/
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public DirectedEdge(int v, int w, double weight) {
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if (v < 0) throw new IndexOutOfBoundsException("Vertex names must be nonnegative integers");
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if (w < 0) throw new IndexOutOfBoundsException("Vertex names must be nonnegative integers");
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if (Double.isNaN(weight)) throw new IllegalArgumentException("Weight is NaN");
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this.v = v;
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this.w = w;
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this.weight = weight;
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}
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/**
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* Returns the tail vertex of the directed edge.
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* @return the tail vertex of the directed edge
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*/
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public int from() {
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return v;
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}
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/**
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* Returns the head vertex of the directed edge.
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* @return the head vertex of the directed edge
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*/
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public int to() {
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return w;
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}
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/**
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* Returns the weight of the directed edge.
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* @return the weight of the directed edge
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*/
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public double weight() {
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return weight;
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}
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/**
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* Returns a string representation of the directed edge.
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* @return a string representation of the directed edge
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*/
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@Override
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public String toString() {
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return v + "->" + w + " " + String.format("%5.2f", weight);
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}
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/**
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* Unit tests the DirectedEdge data type.
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*/
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public static void main(String[] args) {
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DirectedEdge e = new DirectedEdge(12, 23, 3.14);
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StdOut.println(e);
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}
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}
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