COJ 3018 求1~n之间的素数

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cmath>
 4 #include<algorithm>
 5 #include<queue>
 6 #include<cstring>
 7 #include<ctime>
 8 #define PAU putchar(‘ ‘)
 9 #define ENT putchar(‘\n‘)
10 using namespace std;
11 const int Safe=3;
12 int gcd(int a,int b){return !b?a:gcd(b,a%b);}
13 int mul(int a,int b,int p){
14     int tmp=(a*b-(int)((double)a/p*b+1e-8)*p);
15     return tmp<0?tmp+p:tmp;
16 }
17 int pow(int a,int b,int p){
18     int ans=1;a%=p;
19     for(int i=b;i;i>>=1,a=mul(a,a,p))
20         if(i&1)ans=mul(ans,a,p);
21     return ans;
22 }
23 bool check(int a,int n,int r,int s){
24     int ans=pow(a,r,n),p=ans;
25     for(int i=1;i<=s;i++){
26         ans=mul(ans,ans,n);
27         if(ans==1&&p!=1&&p!=n-1) return true;
28         p=ans;
29     } if(ans!=1)return true;return false;
30 }
31 bool MR(int n){
32     if(n<=1) return false;
33     if(n==2) return true;
34     if(!(n&1)) return false;
35     int r=n-1,s=0;
36     while(!(r&1)) r>>=1,s++;
37     for(int i=0;i<Safe;i++)
38         if(check(rand()%(n-1)+1,n,r,s)) return false;
39     return true;
40 }
41 inline int read(){
42     int x=0,sig=1;char ch=getchar();
43     while(!isdigit(ch)){if(ch==‘-‘)sig=-1;ch=getchar();}
44     while(isdigit(ch))x=10*x+ch-‘0‘,ch=getchar();
45     return x*=sig;
46 }
47 inline void write(int x){
48     if(x==0){putchar(‘0‘);return;}if(x<0)putchar(‘-‘),x=-x;
49     int len=0,buf[15];while(x)buf[len++]=x%10,x/=10;
50     for(int i=len-1;i>=0;i--)putchar(buf[i]+‘0‘);return;
51 }
52 bool first=true;
53 void init(){
54     srand(time(0));
55     int n=read();
56     for(int i=2;i<=n;i++){
57         if(MR(i)){
58             if(first) first=false;
59             else PAU;
60             printf("%d",i);
61         }
62     }
63     return;
64 }
65 void work(){
66     return;
67 }
68 void print(){
69     return;
70 }
71 int main(){init();work();print();return 0;}