Codeforces 414B Mashmokh and ACM

http://codeforces.com/problemset/problem/414/B

题目大意：

题意:一个序列B1,B2...Bl如果是好的,必须满足Bi | Bi + 1(a | b 代表a整除b), 求长度为K,元素大小小于等于N的序列个数

思路:f[i][j] 代表在序列的第i位，当前数字为j的方案数

 #include<cstdio>
 #include<cmath>
 #include<algorithm>
 #include<cstring>
 #include<iostream>
 const int Mod=;
 int f[][];
 int n,K;
 int read(){
     int t=,f=;char ch=getchar();
     while (ch<''||ch>''){if (ch=='-') f=-;ch=getchar();}
     while (''<=ch&&ch<=''){t=t*+ch-'';ch=getchar();}
     return t*f;
 }
 int main(){
     n=read();K=read();
     for (int i=;i<=n;i++)
      f[][i]=;
     for (int i=;i<=K;i++)
      for (int j=;j<=n;j++){
         for (int k=;k<=sqrt(j);k++)
          if (j%k==){
                 f[i][j]=(f[i][j]+f[i-][k])%Mod;
                 if (k*k!=j)
                 f[i][j]=(f[i][j]+f[i-][j/k])%Mod;
          }
      }
     int ans=;
     for (int i=;i<=n;i++)
      ans=(ans+f[K][i])%Mod;
     printf("%d\n",ans);
     return ;
 }