BZOJ_2721_[Violet 5]樱花_数学

#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <stdlib.h>
using namespace std;
#define N 1000050
typedef long long ll;
int n,prime[N],cnt;
bool vis[N];
ll ans,mod=1000000007;
int main() {
    ll i,j;
    ans=1;
    scanf("%d",&n);
    for(i=2;i<=n;i++) {
        if(!vis[i]) {
            prime[++cnt]=i;
            int tmp=n,r=0;
            //while(tmp) r+=tmp/i,tmp/=i;
            for(j=i;j>=i&&j<=n;j*=i) {
                r+=n/j;
            }
            ans=ans*(2*r+1)%mod;
        }
        for(j=1;j<=cnt&&i*prime[j]<=n;j++) {
            vis[i*prime[j]]=1;
            if(i%prime[j]==0) break;
        }
    }
    printf("%lld\n",ans);
}