``` 001 002 003 004 005 006 007 008 009 010 011 012 013 014 015 016 017 018 019 020 021 022 023 024 025 026 027 028 029 030 031 032 033 034 035 036 037 038 039 040 041 042 043 044 045 046 047 048 049 050 051 052 053 054 055 056 057 058 059 060 061 062 063 064 065 066 067 068 069 070 071 072 073 074 075 076 077 078 079 080 081 082 083 084 085 086 087 088 089 090 091 092 093 094 095 096 097 098 099 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 ``` ```package algs21; import stdlib.*; // Exercise 2.1.14 /** * Complete the following method to sort a deck of cards, * with the restriction that the only allowed operations are to look * at the values of the top two cards, to exchange the top two cards, * and to move the top card to the bottom of the deck. */ public class MyDeckSort { public static void sort (MyDeck d) { // TODO // You must sort the Deck using only the public methods of Deck. // It should be sufficient to use the following: // d.size (); // d.moveTopToBottom (); // d.topGreaterThanNext (); // d.swapTopTwo (); // While debugging, you will want to print intermediate results. // You can use d.toString() for that: // StdOut.format ("i=%-3d %s\n", i, d.toString ()); } private static double time; private static void countops (MyDeck d) { boolean print = true; if (print) StdOut.println (d.toString ()); d.moveTopToBottom (); if (print) StdOut.println (d.toString ()); Stopwatch sw = new Stopwatch (); sort (d); time = sw.elapsedTime (); if (print) StdOut.println (d.toString ()); d.isSorted (); } public static void main (String[] args) { int N = 10; MyDeck d = new MyDeck (N); countops (d); //System.exit (0); // Comment this out to do a doubling test! double prevOps = d.ops (); double prevTime = time; for (int i = 0; i < 12; i++) { N *= 2; d = new MyDeck (N); countops (d); StdOut.format ("%8d %10d %5.1f [%5.3f %5.3f]\n", N, d.ops (), d.ops () / prevOps, time, time / prevTime); prevOps = d.ops (); prevTime = time; } } } /** * The Deck class has the following API: * *
* MyDeck (int N)                 // create a randomized Deck of size N  * int size ()                    // return the size of N  * int ops ()                     // return the number of operations performed on this Deck  * boolean topGreaterThanNext ()  // compare top two items  * void swapTopTwo ()             // swap top two itens  * void moveTopToBottom ()        // move top item to bottom  * void isSorted ()               // check if isSorted (throws exception if not)  *
*/ class MyDeck { private int N; private int top; private long ops; private int[] a; public long ops () { return ops; } public int size () { return N; } public MyDeck (int N) { this.N = N; this.top = 0; this.ops = 0; this.a = new int[N]; for (int i = 0; i < N; i++) a[i] = i; StdRandom.shuffle (a); } public boolean topGreaterThanNext () { int i = a[top]; int j = a[(top + 1) % N]; ops += 2; return i > j; } public void swapTopTwo () { int i = a[top]; int j = a[(top + 1) % N]; a[top] = j; a[(top + 1) % N] = i; ops += 4; } public void moveTopToBottom () { top = (top + 1) % N; ops += 1; } public String toString () { StringBuilder b = new StringBuilder (); b.append ('['); for (int i = top;;) { b.append (a[i]); i = (i + 1) % N; if (i == top) return b.append (']').toString (); b.append (", "); } } public void isSorted () { boolean print = false; long theOps = ops; // don't count the operations require by isSorted for (int i = 1; i < N; i++) { if (print) StdOut.format ("i=%-3d %s\n", i, toString ()); if (topGreaterThanNext ()) throw new Error (); moveTopToBottom (); } if (print) StdOut.format ("i=%-3d %s\n", N, toString ()); moveTopToBottom (); if (print) StdOut.format ("i=%-3d %s\n", N + 1, toString ()); ops = theOps; } } ```