[数据结构与算法]Codeforces Round #774 (Div. 2) E. Power Board

#include <iostream>
#include <stdio.h>
#include <string.h>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <vector>
#include <math.h>
#include <bitset>
#include <algorithm>
#include <climits>
using namespace std;
// using namespace std;
#define int long long
const int N = 2000000,mod = 1e9+7;
int n,m,vis[N*10],a[25],b[N];
int32_t main(){
	scanf("%lld%lld",&n,&m);
	int cnt=0;
	for(int i=1;i<=20;i++){
		for(int j=1;j<=m;j++){
			if(!vis[i*j]){
				vis[i*j]=1;
				++cnt;
			}
		}
		a[i]=cnt;
	}
	// cout<<cnt<<endl;
	int res=1;
	for(int i=2;i<=n;i++){
		if(b[i]==1) continue;
		int cnt=1;
		for(int j=i;j<=n;j=j*i){
			b[j]=1;
			++cnt;
		}
		--cnt;
		res+=a[cnt];
		// cout<<res<<endl;
	}
	cout<<res<<endl;
	
}