Java似乎是有亿点点慢hhh，第一次发题解ꉂ(ˊᗜˋ*)

题目描述

1. 递归实现排列类型枚举 II

样例

9
1 2 3 4 5 6 7 8 9

Java 代码

import java.util.*;
import java.io.*;

public class Main {

    static int N = 15;
    static boolean[] vis;
    static ArrayList<Integer> path = new ArrayList();
    static int n;

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StreamTokenizer in = new StreamTokenizer(br);
        PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));

        while (in.nextToken() != StreamTokenizer.TT_EOF) {
            n = (int) in.nval;
            int[] a = new int[n];
            for (int i = 0; i < n; ++i) {
                in.nextToken();
                a[i] = (int) in.nval;
            }
            Arrays.sort(a);
            vis = new boolean[N];
            dfs(0, a, out);

        }
    }

    public static void dfs(int idx, int[] a, PrintWriter out) {
        if (idx == n) {
            for (int i = 0; i < n; ++i) {
                out.print(path.get(i) + " ");
            }
            out.println();
            out.flush();
            return;
        }
        for (int i = 0; i < n; ++i) {
            if (vis[i] || (i > 0 && a[i] == a[i - 1] && !vis[i - 1])) {
                continue;
            }
            path.add(a[i]);
            vis[i] = true;
            dfs(idx + 1, a, out);
            vis[i] = false;
            path.remove(path.size() - 1);
        }
    }

}