BEAKJOON JAVA ALGORITHM #10844(쉬운 계단 수)

https://www.acmicpc.net/problem/10844

import java.util.Scanner; public class a10844 { public static void main(String[] args) { Scanner sc = new Scanner(System.in); int num = sc.nextInt(); long[][] arr = new long[num+1][10]; for(int i=1; i<=9; i++) { arr[1][i] = 1; } for(int i=2; i<=num; i++) { arr[i][0] = arr[i-1][1]; arr[i][9] = arr[i-1][8]; for(int j=1; j<=8; j++) { arr[i][j] = arr[i-1][j-1] + arr[i-1][j+1]; arr[i][j] %= 1000000000; } } long sum = 0; for(int i=0; i<=9; i++) { sum += arr[num][i]; } System.out.println(sum % 1000000000); } }