51nod1536-素数&猜测-不一样的猜数游戏

#include <bits/stdc++.h>
using namespace std;
/* 素数筛
*/
const int maxn=1e4;
vector<int>q;
int m;
int  vis[maxn];
void jud(){
memset(vis,-1,sizeof(vis));
q.clear();
for(int i=2;i<=maxn;i++){
if(vis[i]==-1){
vis[i]=1;
//q.push_back(i);
//cout<<i<<endl;
for(int j=i*2;j<=maxn;j+=i){
//cout<<j<<endl;
vis[j]=0;
}
}
}
}
int main()
{   jud();
while(~scanf("%d",&m)){
int kk=0;
int ans=0;
for(int i=2;i<=m;i++){
if(vis[i]==1){
int j=i;
kk++;
while(j<=m){
ans++;
j*=i;
}

}
}
//cout<<kk<<endl;
printf("%d\n",ans);

}

return 0;
}