数组的所有可能组合 [英] All possible combinations of an array

问题描述

我有一个字符串数组

{"ted", "williams", "golden", "voice", "radio"}

并且我想要以下形式的这些关键字的所有可能组合:

and I want all possible combinations of these keywords in the following form:

{"ted",
 "williams",
 "golden", 
 "voice", 
 "radio",
 "ted williams", 
 "ted golden", 
 "ted voice", 
 "ted radio", 
 "williams golden",
 "williams voice", 
 "williams radio", 
 "golden voice", 
 "golden radio", 
 "voice radio",
 "ted williams golden", 
 "ted williams voice", 
 "ted williams radio", 
 .... }

我已经使用了几个小时没有任何有效结果(高级编程的副作用??).

I've been going for hours with no effective result (side effect of high-level programming ??).

我知道解决方案应该是显而易见的，但老实说，我被卡住了！接受 Java/C# 中的解决方案.

I know the solution should be obvious but I'm stuck, honestly ! Solutions in Java/C# are accepted.

编辑:

1. 这不是家庭作业
2. ted williams"和williams ted"被认为是一样的，所以我只想要ted williams"

EDIT 2:查看答案中的链接后，发现 Guava 用户可以在 com.google.common.collect.Sets 中使用 powerset 方法

EDIT 2: after reviewing the link in the answer, it turns out that Guava users can have the powerset method in com.google.common.collect.Sets

推荐答案

正如 FearUs 指出的那样，更好的解决方案是使用 Guava 的 Sets.powerset(Set set).

As FearUs pointed out, a better solution is to use Guava's Sets.powerset(Set set).

编辑 2: 更新了链接.

对的快速而肮脏的翻译这个解决方案:

public static void main(String[] args) {

    List<List<String>> powerSet = new LinkedList<List<String>>();

    for (int i = 1; i <= args.length; i++)
        powerSet.addAll(combination(Arrays.asList(args), i));

    System.out.println(powerSet);
}

public static <T> List<List<T>> combination(List<T> values, int size) {

    if (0 == size) {
        return Collections.singletonList(Collections.<T> emptyList());
    }

    if (values.isEmpty()) {
        return Collections.emptyList();
    }

    List<List<T>> combination = new LinkedList<List<T>>();

    T actual = values.iterator().next();

    List<T> subSet = new LinkedList<T>(values);
    subSet.remove(actual);

    List<List<T>> subSetCombination = combination(subSet, size - 1);

    for (List<T> set : subSetCombination) {
        List<T> newSet = new LinkedList<T>(set);
        newSet.add(0, actual);
        combination.add(newSet);
    }

    combination.addAll(combination(subSet, size));

    return combination;
}

测试:

$ java PowerSet ted williams golden
[[ted], [williams], [golden], [ted, williams], [ted, golden], [williams, golden], [ted, williams, golden]]
$

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