[BOJ] 백준 1038 감소하는 수

[문제]

https://www.acmicpc.net/problem/1038

 

 

[소스 코드]

import java.io.*;
import java.util.*;
public class Main {
	static List<Long> list = new ArrayList<>();
    public static void main(String[] args) throws IOException {
    	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    	int n = Integer.parseInt(br.readLine());
    	if(n<10) System.out.println(n);
    	else if(n>=1023) System.out.println(-1);
    	else {
    		for(int i=0;i<10;i++) {
    			solve(i,1);
    		}
    		Collections.sort(list);
    		System.out.println(list.get(n));
    	}
    }
    private static void solve(long num,int idx) {
    	if(idx>10) return;
    	list.add(num);
    	for(int i=0;i<num%10;i++) {
			solve(num*10+i,idx+1);
		}
    }
}