动态规划之K好数（蓝桥杯ALGO-3）

import java.util.Scanner;public class Demo01 {private int[][] matrix(int k, int l){int[][] matrix = new int[l][k];for(int i = 0; i < k; i ++){matrix[0][i] = 1;}matrix[0][0] = 0;for(int i = 1; i < l; i ++){for(int j = 0; j < k; j ++){for(int n = 0; n < k; n ++){if((n - j) != 1 && (j - n) != 1){matrix[i][j] = (matrix[i][j] + matrix[i - 1][n]) % 1000000007;}}}}int count = 0;for(int i = 0; i < k ; i ++){count = (count + matrix[l - 1][i]) % 1000000007;}System.out.println(count);return matrix;}public static void main(String[] args) {Scanner sc = new Scanner(System.in);int k = sc.nextInt();int l = sc.nextInt();new Demo01().matrix(k, l);}}