[BOJ] 15988 1, 2, 3 더하기 3 (JAVA)

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

15988번: 1, 2, 3 더하기 3

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
	
    public static void main(String[] args) throws Exception {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb = new StringBuilder();
        long[] dp = new long[1_000_001];
        dp[1] = 1;
        dp[2] = 2;
        dp[3] = 4;
        for (int i = 4; i < 1_000_001; i++) {
            dp[i] = (dp[i - 1] + dp[i - 2] + dp[i - 3]) % 1_000_000_009;
        }

        int T = Integer.parseInt(br.readLine());
        for (int tc = 0; tc < T; tc++) {
            sb.append(dp[Integer.parseInt(br.readLine())]).append("\n");
        }

        System.out.print(sb);

    }

}