题目描述

blablabla

样例

blablabla

算法1

blablabla

时间复杂度

参考文献

代码

import java.io.*;

class Main{
    static StreamTokenizer in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
    static PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));

    static int nextInt() throws Exception{
        in.nextToken();
        return (int)in.nval;
    } 

    static int[] st, ans;
    static int size, n; 

    static void DFS(int top, int d, int cnt){
        if(size >= 20) return;
        if(cnt==n){
            size++;
            for(int i=0;i<n;i++) out.print(ans[i]);
            out.println("");
            return;
        }

        if(top>-1){
            ans[cnt] = st[top];
            DFS(top-1, d, cnt+1); 
            st[top] = ans[cnt];
        }

        if(d<=n){
            st[top+1] = d;
            DFS(top+1, d+1, cnt);    
        }

    }

    public static void main(String[] args) throws Exception{
        n = nextInt();
        st = new int[n+1];
        ans = new int[n+1];
        size = 0;
        DFS(-1, 1, 0);
        out.close();
    }
}