备战NOIP——模板复习11
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2022-03-23 10:46:55
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这里只有模板,并不作讲解,仅为路过的各位做一个参考以及用做自己复习的资料,转载注明出处。
素数筛
埃氏筛
/*Copyright: Copyright (c) 2018
*Created on 2018-11-02
*Author: 十甫
*Version 1.0
*Title: 埃氏筛
*Time: 3 mins
*/
#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
const int size = 100005;
bool prime[size];
inline void make(int n) {
memset(prime, true, sizeof(prime));
prime[1] = false;
for(int i = 2;i <= n;i++) if(prime[i]) {
for(int j = i * 2;j <= n;j += i) {
prime[j] = false;
}
}
}
int main() {
int n;
scanf("%d", &n);
make(n);
int q;
while(q--) {
int k;
scanf("%d", &k);
printf("%d\n", prime[k]);
}
return 0;
}
欧拉筛
/*Copyright: Copyright (c) 2018
*Created on 2018-11-02
*Author: 十甫
*Version 1.0
*Title: 欧拉筛
*Time: 3.5 mins
*/
#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
const int size = 100005;
int prime[size];
bool flag[size];
inline void make_prime(int n) {
for(int i = 2;i <= n;i++) {
if(!flag[i]) {
prime[++prime[0]] = i;
}
for(int j = 1;j <= prime[0] && prime[j] * i <= n;j++) {
flag[prime[j] * i] = true;
if(!(i % prime[j])) break;
}
}
}
int main() {
int n;
scanf("%d", &n);
make_prime(n);
for(int i = 1;i <= prime[0];i++) {
printf("%d ", prime[i]);
}
printf("\n");
return 0;
}
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