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| -rw-r--r-- | src/algorithms/shuffling/HumanShuffle.java | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/src/algorithms/shuffling/HumanShuffle.java b/src/algorithms/shuffling/HumanShuffle.java new file mode 100644 index 0000000..cfdc6b9 --- /dev/null +++ b/src/algorithms/shuffling/HumanShuffle.java @@ -0,0 +1,62 @@ +/** + * Copyright © 2014 Mattias Andrée (maandree@member.fsf.org) + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU Affero General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU Affero General Public License for more details. + * + * You should have received a copy of the GNU Affero General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ +package algorithms.arrays; + +import java.util.Random; + + +/** + * Bias free array shuffling class aiming to imitate naïve shuffling as preformed by humans + */ +public class HumanShuffle +{ +£>for T in boolean char byte short int long float double Object; do + /** + * Shuffles an array + * + * @param array The array to shuffle + * @param random The random generator to use + */ + public static void shuffle(£{T}[] array, Random random) + { + int n; + if ((n = array.length) < 2) + return; + + int min = (int)(random.nextGaussian() * n) >> 1; + if (min < 0) + min = n - min; + else + min += n; + + int k = 0; + while ((k++ < min) || (random.nextInt(2) == 0)) + { + int i = random.nextInt(n); + int j = random.nextInt(n); + + if (i == j) + j = (j + 1) % n; + + £{T} temp = array[i]; + array[i] = array[j]; + array[j] = temp; + } + } +£>done +} + |