``` 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 ``` ```// Exercise 1.5.7 (Solution published at http://algs4.cs.princeton.edu/) package algs15; import java.util.Arrays; import stdlib.*; /* ************************************************************************** * Compilation: javac QuickFindUF.java * Execution: java QuickFindUF < input.txt * Dependencies: StdIn.java StdOut.java * * Quick-find algorithm. * * % java QuickFindUF < largeUF.txt * QuickFindUF # components: 6 [1054.198000] // 17 minutes * ****************************************************************************/ public class QuickFindUF implements UF { private int[] id; private int count; // instantiate N isolated components 0 through N-1 public QuickFindUF(int N) { count = N; id = new int[N]; for (int i = 0; i < N; i++) id[i] = i; } // return number of connected components public int count() { return count; } // Return component identifier for component containing p public int find(int p) { return id[p]; } // are elements p and q in the same component? public boolean connected(int p, int q) { return id[p] == id[q]; } // merge components containing p and q public void union(int p, int q) { if (connected(p, q)) return; int pid = id[p]; // loser int qid = id[q]; // champion for (int i = 0; i < id.length; i++) if (id[i] == pid) id[i] = qid; count--; } public String toString() { return Arrays.toString (id); } public static void main(String[] args) { StdIn.fromFile ("data/tinyUF.txt"); //StdIn.fromFile ("data/mediumUF.txt"); //StdIn.fromFile ("data/largeUF.txt"); int N = StdIn.readInt(); QuickFindUF uf = new QuickFindUF(N); // read in a sequence of pairs of integers (each in the range 0 to N-1), // calling find() for each pair: If the members of the pair are not already // call union() and print the pair. Stopwatch sw = new Stopwatch (); while (!StdIn.isEmpty()) { int p = StdIn.readInt(); int q = StdIn.readInt(); if (uf.connected(p, q)) continue; uf.union(p, q); StdOut.println(p + " " + q); GraphvizBuilder.ufToFile (uf.id); } StdOut.format("QuickFindUF # components: %d [%f]\n", uf.count(), sw.elapsedTime ()); } } ```