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Change-Id: I35b3ceb1ac2aa7fc4e26a28ff814bccba6bbb004 Reviewed-on: https://dart-review.googlesource.com/7200 Commit-Queue: Jaime Wren <jwren@google.com> Reviewed-by: Jaime Wren <jwren@google.com>
93 lines
2.3 KiB
Dart
93 lines
2.3 KiB
Dart
// Copyright (c) 2011, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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// The Great Computer Language Shootout
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// http://shootout.alioth.debian.org/
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// Ported from JavaScript contributed by Isaac Gouy.
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// Description: Repeatedly access a tiny integer-sequence.
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import "package:expect/expect.dart";
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class FannkuchTest {
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static fannkuch(n) {
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var p = new List(n), q = new List(n), s = new List(n);
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var sign = 1, maxflips = 0, sum = 0, m = n - 1;
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for (var i = 0; i < n; i++) {
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p[i] = i;
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q[i] = i;
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s[i] = i;
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}
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do {
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// Copy and flip.
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var q0 = p[0]; // Cache 0th element.
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if (q0 != 0) {
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for (var i = 1; i < n; i++) q[i] = p[i]; // Work on a copy.
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var flips = 1;
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do {
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var qq = q[q0];
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if (qq == 0) {
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// ... until 0th element is 0.
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sum += sign * flips;
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if (flips > maxflips) maxflips = flips; // New maximum?
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break;
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}
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q[q0] = q0;
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if (q0 >= 3) {
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var i = 1, j = q0 - 1, t;
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do {
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t = q[i];
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q[i] = q[j];
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q[j] = t;
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i++;
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j--;
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} while (i < j);
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}
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q0 = qq;
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flips++;
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} while (true);
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}
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if (sign == 1) {
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var t = p[1];
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p[1] = p[0];
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p[0] = t;
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sign = -1; // Rotate 0<-1.
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} else {
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// Rotate 0<-1 and 0<-1<-2.
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var t = p[1];
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p[1] = p[2];
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p[2] = t;
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sign = 1;
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for (var i = 2; i < n; i++) {
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var sx = s[i];
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if (sx != 0) {
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s[i] = sx - 1;
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break;
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}
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if (i == m) {
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return [sum, maxflips];
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}
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s[i] = i;
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// Rotate 0<-...<-i+1.
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t = p[0];
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for (var j = 0; j <= i; j++) {
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p[j] = p[j + 1];
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}
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p[i + 1] = t;
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}
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}
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} while (true);
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}
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static testMain() {
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var n = 6;
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var pf = fannkuch(n);
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Expect.equals(49, pf[0]);
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Expect.equals(10, pf[1]);
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print("${pf[0]}\nPfannkuchen($n) = ${pf[1]}");
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}
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}
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main() {
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FannkuchTest.testMain();
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}
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