蓝桥杯 算法训练 K好数 JAVA

import java.util.Scanner;

class Main{
	static int MOD=1000000007 ;
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int k = sc.nextInt();
		int l = sc.nextInt();
		int dp[][] = new int[101][101];
		for (int i = 0; i < k; i++) {
			dp[1][i] = 1;
		}
		for (int i = 2; i <=l; i++) {
			for (int j = 0; j < k; j++) {
				for (int j2 = 0; j2 < k; j2++) {
					if(j2 != j-1 && j2 != j+1){
						dp[i][j] += dp[i-1][j2];
						dp[i][j] %= MOD; 
					}
				}
			}
		}
		int sum = 0;
		for (int i = 1; i < k; i++) {
			sum+= dp[l][i];
			sum %= MOD;
		}
		System.out.println(sum);
		
	}
}