ZOJ 4011 Happy Sequence

Happy Sequence (151 - ZOJ Monthly, March 2018 - H)

http://acm.zju.edu.cn/onlinejudge/showContestProblem.do?problemId=5719

Sample Input

1
3 2

Sample Output

5

Hint

In the sample test case, the happy sequences are: , , , , .

Code

#include <iostream>
#include <cstdio>
using namespace std;

const int maxn = 2000 + 10;
const int mod = 1000000000 + 7;

int dp[maxn][maxn];

int main(){
    for(int i = 1;i <= 2000;i ++){
            dp[1][i] = 1;
        }
    for(int i = 1;i <= 2000;i ++){
        for(int j = 1;j <= 2000;j ++){
            if(dp[i][j]){
                for(int k = 1;k <= 2000 / j;k ++){
                    dp[i + 1][k * j] += dp[i][j];
                    dp[i + 1][k * j] %= mod;
                }
            }
        }
    }
    int t;
    scanf("%d",&t);
    while(t --){
        int n,m;
        scanf("%d%d",&n,&m);
        int sum = 0;
        for(int i = 1;i <= n;i ++){
            sum += dp[m][i];
            sum %= mod;
        }
        printf("%d\n",sum);
    }
    return 0;
}