org.xmlcml.util.Partition Maven / Gradle / Ivy
/**
* Copyright 2011 Peter Murray-Rust et. al.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.xmlcml.util;
import java.util.ArrayList;
import java.util.List;
import org.apache.log4j.Logger;
import org.xmlcml.euclid.Util;
/**
*
* @author pm286
*
*/
public class Partition {
private static Logger LOG = Logger.getLogger(Partition.class);
/**
* returns all the ways the integer provided can be divided
* into whole number parts. This supplying 5 returns
*
* 1 1 1 1 1
* 2 1 1 1
* 2 2 1
* 3 1 1
* 3 2
* 4 1
* 5
*
* @param n
* @return list
*/
public static List> partition(int n) {
List> partitionList = new ArrayList>();
List partition = new ArrayList();
return partition(n, n, "", partitionList, partition);
}
private static List> partition(int n, int max, String prefix,
List> partitionList,
List partition) {
if (n == 0) {
//LOG.debug(prefix);
partitionList.add(new ArrayList(partition));
partition.clear();
return partitionList;
}
for (int i = Math.min(max, n); i >= 1; i--) {
//LOG.debug(prefix + " " + i);
partition.add(i);
partition(n-i, i, prefix + " " + i, partitionList, partition);
}
return partitionList;
}
/** main.
*
* @param args
*/
public static void main(String[] args) {
List> partitionList = partition(5);
for (List partition : partitionList) {
for (Integer in : partition) {
Util.println(" ");
}
LOG.debug("");
}
}
}
© 2015 - 2025 Weber Informatics LLC | Privacy Policy