[백준] 1, 2, 3 더하기 3 15988 - JAVA

문제

https://www.acmicpc.net/problem/15988

15988번: 1, 2, 3 더하기 3

 

코드

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

class Main {
	
	public static void main(String args[]) throws Exception{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));		
		StringBuilder sb = new StringBuilder();
		
		int T = Integer.parseInt(br.readLine());
		
		long dp [] = new long [1000001];
		
		dp[1] = 1;
		dp[2] = 2;
		dp[3] = 4;
		
		for(int i=4;i<=1000000;i++) {
			dp[i] = dp[i-1] + dp[i-2] + dp[i-3];
			dp[i] = dp[i] % 1000000009;
		}
		
		for(int t=0;t<T;t++) {
			int n = Integer.parseInt(br.readLine());
			sb.append(dp[n]).append("\n");
		}
		System.out.print(sb);
		
		
	}

}