第十四届蓝桥杯集训——练习解题阶段(无序阶段)-ALGO-3 算法训练 K好数

#include<stdio.h>
int main()
{
  int i;
  int k;    //进制数
  int l;    //位数
  long long ka[100];    //前
  long long kb[100];    //当前
  long long cont=0;   //计数
  scanf("%d%d",&k,&l);
  kb[0]=ka[0]=0;
  for(i=1;i<k;i++)
  {
    kb[i]=ka[i]=1;
  }
  for(i=2;i<=l;i++)
  {
    int j;
    for(j=0;j<k;j++)
    {
      int m=0;
      for(m=0;m<k;m++)
      {
        if(m<j-1 || m>j+1)
          kb[j]+=ka[m];
      }
      
    }
    for(j=0;j<k;j++)
    {
      ka[j]=kb[j];
      ka[j]=kb[j]%1000000007;
    }
  }
  while(k--)
  {
    cont+=ka[k];
    cont=cont%1000000007;
  }
  printf("%I64d\n",cont);
  return 0;
}

#include <iostream>
using namespace std;
int main(int argc, char** argv) {
  int k,l;
  cin>>k>>l;
  long long table[100][100];
  for(int i=0;i<k;i++)
  {
    table[0][i]=1ll;
  }
  table[0][0]=0ll;
  for(int i=1;i<l;i++)
  {
    for(int j=0;j<k;j++)
    {
      long long  x=0;
      for(int y=0;y<k;y++)
      {
        if(y!=j+1 && y!=j-1)
        {
          x+=table[i-1][y];
        }
      }
      table[i][j]=x%1000000007ll;
    }
  }
  long long count=0;
  for(int i=0;i<k;i++)
  {
    count+=table[l-1][i];
  }
  cout<<(count%1000000007ll);
  return 0;
}

import java.util.Scanner;
public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int l = sc.nextInt();
        sc.close();
    int[][] dp = new int[l][k];
        /*0不能作为首位*/
        for (int i=1; i<k; i++){    //第一行后(k-1)个元素都为1
            dp[0][i] = 1;
        }
        for (int i=1; i<l; i++){
            for (int j=0; j<k; j++){
                dp[i][j] = otherCount(dp[i-1], j);
            }
        }
        int result = 0;
        for (int i : dp[l-1])
            result =(result + i) % 1000000007;
        System.out.println(result);
    }
    public static int otherCount(int[] dp_row, int n){
        int sum = 0;
        for (int i=0; i<dp_row.length; i++){
            if (i+1 == n || i-1 ==n){
                continue;
            }
            sum = (sum + dp_row[i]) % 1000000007;
        }
        return sum;
    }
}

k,l = map(int,input().split())
sum = [[0 for _ in range(l)]for _ in range(k)]
for i in range(k):
    sum[i][0] = 1 
for i in range(1,l):
    z = 0
    for g in range(k):
        z = z+sum[g][i-1]
    for j in range(k):
        sum[j][i]=z
        if j-1 != -1:
            sum[j][i]=sum[j][i]-sum[j-1][i-1]
        if j+1 != k:
            sum[j][i]=sum[j][i]-sum[j+1][i-1]
z = 0
for i in range(1,k):
    z = z+sum[i][l-1]
print(z%1000000007)