69 lines
1.3 KiB
Java
69 lines
1.3 KiB
Java
package org.rosettacode.java;
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import java.util.Arrays;
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import java.util.stream.IntStream;
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public class HeapsAlgorithm {
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public static void main(String[] args) {
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Object[] array = IntStream.range(0, 4)
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.boxed()
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.toArray();
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HeapsAlgorithm algorithm = new HeapsAlgorithm();
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algorithm.recursive(array);
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System.out.println();
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algorithm.loop(array);
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}
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void recursive(Object[] array) {
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recursive(array, array.length, true);
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}
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void recursive(Object[] array, int n, boolean plus) {
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if (n == 1) {
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output(array, plus);
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} else {
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for (int i = 0; i < n; i++) {
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recursive(array, n - 1, i == 0);
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swap(array, n % 2 == 0 ? i : 0, n - 1);
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}
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}
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}
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void output(Object[] array, boolean plus) {
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System.out.println(Arrays.toString(array) + (plus ? " +1" : " -1"));
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}
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void swap(Object[] array, int a, int b) {
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Object o = array[a];
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array[a] = array[b];
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array[b] = o;
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}
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void loop(Object[] array) {
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loop(array, array.length);
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}
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void loop(Object[] array, int n) {
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int[] c = new int[n];
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output(array, true);
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boolean plus = false;
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for (int i = 0; i < n; ) {
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if (c[i] < i) {
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if (i % 2 == 0) {
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swap(array, 0, i);
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} else {
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swap(array, c[i], i);
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}
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output(array, plus);
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plus = !plus;
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c[i]++;
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i = 0;
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} else {
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c[i] = 0;
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i++;
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}
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}
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}
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}
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