题目网址: http://codeforces.com/problemset/problem/414/B
Description
Mashmokh‘s boss, Bimokh, didn‘t like Mashmokh. So he fired him. Mashmokh decided to go to university and participate in ACM instead of finding a new job. He wants to become a member of Bamokh‘s team. In order to join he was given some programming tasks and one week to solve them. Mashmokh is not a very experienced programmer. Actually he is not a programmer at all. So he wasn‘t able to solve them. That‘s why he asked you to help him with these tasks. One of these tasks is the following.
A sequence of l integers b1, b2, ..., bl(1 ≤ b1 ≤ b2 ≤ ... ≤ bl ≤ n) is called good if each number divides (without a remainder) by the next number in the sequence. More formally for all i(1 ≤ i ≤ l - 1).
Given n and k find the number of good sequences of length k. As the answer can be rather large print it modulo 1000000007(109 + 7).
Input
The first line of input contains two space-separated integers n, k (1 ≤ n, k ≤ 2000).
Output
Output a single integer — the number of good sequences of length k modulo 1000000007(109 + 7).
Sample Input
Input
3 2
Output
5
Input
6 4
Output
39
Input
2 1
Output
2
Hint
In the first sample the good sequences are: [1, 1], [2, 2], [3, 3], [1, 2], [1, 3].
#include <stdio.h> #include <string.h> #include <iostream> using namespace std ; const int N=2010; const int mod=1e9+7; int dp[N][N]; //dp[i][j]表示长度为i,最后一个元素为j的序列数。 int main() { int n,k; while(cin>>n>>k) { memset(dp,0,sizeof(dp)); for(int i=1;i<=n;i++) dp[1][i]=1; for(int t=1;t<k;t++) { for(int i=1;i<=n;i++) { for(int j=1;i*j<=n;j++) { dp[t+1][i*j]+=dp[t][i];//从i=1循环到n,i*j即凡是i的倍数的dp值均加上上一行(序列长度少一)的dp[t][i]值。 dp[t+1][i*j]%=mod; } } } int set=0; for(int i=1;i<=n;i++) { set+=dp[k][i]; set%=mod; } cout<<set<<endl; } return 0 ; }