Java List Permutate perm(List l)

Description

perm

License

Open Source License

Declaration

public static <T> List<List<T>> perm(List<T> l) 

Method Source Code

//package com.java2s;
/*//from   ww  w  .  ja v a  2s  .  c o m
 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code 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 General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

import java.util.*;

public class Main {
    public static <T> List<List<T>> perm(List<T> l) {
        List<List<T>> result = new ArrayList<>();
        for (int i = 0; i < l.size(); i++) {
            for (List<T> perm : perm(sub(l, i))) {
                perm.add(0, l.get(i));
                result.add(perm);
            }
        }
        result.add(new ArrayList<T>());

        return result;
    }

    private static <T> List<T> sub(List<T> l, int index) {
        List<T> subL = new ArrayList<>(l);
        subL.remove(index);
        return subL;
    }
}

Related

1. permsList(List topList)
2. permutate(List src)
3. permutation(List list1, List list2, String token)
4. permutation(String prefix, String s, List list)