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]
) % 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);
}
}