[算法]计算全排列组合数

求一个字符串的全排列所有情况。

输入：

2

输出：

012
021
102
120
201
210
6

代码实现：

package com.darrenchan;

import java.util.*;

public class Yongyou {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int n = scanner.nextInt();
String[] array = new String[n + 1];
for (int i = 0; i <= n; i++) {
array[i] = i + "";
}
List<String> list = new ArrayList<>();
listAll(Arrays.asList(array), "", array.length, list);
for (String s : list) {
System.out.println(s);
}
System.out.println(list.size());
}

public static void listAll(List candidate, String prefix, int n, List<String> list){
if (prefix.length() == n) {
list.add(prefix);
}
for (int i = 0; i < candidate.size(); i++) {
List tmp = new LinkedList(candidate);
listAll(tmp, prefix + tmp.remove(i), n, list);//函数中的参数从右边开始解析
}
}

}