``` 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 75 76 77 78 79 80 81 ``` ```package algs43; import stdlib.*; /* *********************************************************************** * Compilation: javac Edge.java * Execution: java Edge * * Immutable weighted edge. * *************************************************************************/ /** * The Edge class represents a weighted edge in an undirected graph. *

* For additional documentation, see Section 4.3 of * Algorithms, 4th Edition by Robert Sedgewick and Kevin Wayne. */ public class Edge implements Comparable { private final int v; private final int w; private final double weight; /** * Create an edge between v and w with given weight. */ public Edge(int v, int w, double weight) { this.v = v; this.w = w; this.weight = weight; } /** * Return the weight of this edge. */ public double weight() { return weight; } /** * Return either endpoint of this edge. */ public int either() { return v; } /** * Return the endpoint of this edge that is different from the given vertex * (unless a self-loop). */ public int other(int vertex) { if (vertex == v) return w; else if (vertex == w) return v; else throw new Error("Illegal endpoint"); } /** * Compare edges by weight. */ public int compareTo(Edge that) { if (this.weight() < that.weight()) return -1; else if (this.weight() > that.weight()) return +1; else return 0; } /** * Return a string representation of this edge. */ public String toString() { return String.format("%d--%d %.2f", v, w, weight); } /** * Test client. */ public static void main(String[] args) { Edge e = new Edge(12, 23, 3.14); StdOut.println(e); } } ```