``` 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 ``` ```package algs44; import stdlib.*; /* *********************************************************************** * Compilation: javac DirectedEdge.java * Execution: java DirectedEdge * * Immutable weighted directed edge. * *************************************************************************/ /** * The DirectedEdge class represents a weighted edge in an directed graph. *

* For additional documentation, see Section 4.4 of * Algorithms, 4th Edition by Robert Sedgewick and Kevin Wayne. */ public class DirectedEdge implements Comparable { private final int v; private final int w; private final double weight; /** * Create a directed edge from v to w with given weight. */ public DirectedEdge(int v, int w, double weight) { this.v = v; this.w = w; this.weight = weight; } /** * Return the vertex where this edge begins. */ public int from() { return v; } /** * Return the vertex where this edge ends. */ public int to() { return w; } /** * Return the weight of this edge. */ public double weight() { return weight; } /** * Return a string representation of this edge. */ public String toString() { return String.format("%d->%d %.2f", v, w, weight); } /** * Compare by weights. */ public int compareTo (DirectedEdge o) { if (weight < o.weight) return -1; if (weight > o.weight) return 1; return 0; } /** * Test client. */ public static void main(String[] args) { DirectedEdge e = new DirectedEdge(12, 23, 3.14); StdOut.println(e); } } ```