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seive of eratosthenes(final).cpp
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seive of eratosthenes(final).cpp
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#include<bits/stdc++.h>
///...................................*****.................................................///
/// Author : Raihan Khan Raka ( raihankhanraka@gmail.com ) ///
/// Department of Computer Science ///
/// & Engineering ///
/// Comilla University , Bangladesh.
///
///...................................*****.................................................///
/*....................................Values................................................*/
#define p5 100007
#define p6 1000007
#define PI acos(-1)
#define M 1000000007
#define inf 1LL << 62
#define white 0
#define gray 1
#define black 2
/*....................................Functions.............................................*/
#define sqr(x) x*x
#define sc scanf
#define pf printf
#define pfn printf("\n")
#define scin(x) sc("%d",&(x))
#define scin2(xx,zz) scanf("%d %d",&xx,&zz)
#define scln(x) sc("%lld",&(x))
#define scln2(xx,zz) scanf("%lld %lld",&xx,&zz)
#define min3(a,b,c) min(a,min(b,c))
#define max3(a,b,c) max(a,max(b,c))
#define all(v) v.begin(), v.end()
#define ok cout << "ok" << endl
#define mem(x,y) memset(x,y,sizeof(x))
#define clr(a) a.clear()
#define READ(f) freopen(f, "r", stdin)
#define WRITE(f) freopen(f, "w", stdout)
/*...................................Data_Types............................................*/
#define lli long long int
#define ull unsigned long long int
#define pii pair < int, int>
#define pll pair < ll, ll>
#define veci vector<int>
#define vecl vector<long long int>
#define vecp vector< pair<int,int> >
#define mapstrint map< string , int >
#define mapstrstr map< string , string >
#define mapint map< int, int >
#define uset unordered_set
#define umap unordered_map
#define pq priority_queue
#define pb push_back
#define mp make_pair
#define ff first
#define ss second
/*.....................................Loops...............................................*/
#define rep( i , a , b ) for( i=a ; i<b ; i++)
#define rev( i , a , b ) for( i=a ; i>=b ; i--)
#define repx( i ,a,b, x) for( i=a ; i<b ; i+=x)
#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
//int month[]={31,28,31,30,31,30,31,31,30,31,30,31};
//long power(long int x, long int y){ int temp; if( y == 0) return 1; temp = power(x, y/2); if (y%2 == 0) return temp*temp; else return x*temp*temp; }
/*lli gcd(lli x,lli y)
{
if(x==0) return y;
return gcd(y%x,x);
}
lli bigmod(lli n, lli k)
{
lli ans=1;
while(k)
{
if(k&1)
ans=(ans*n)%M;
k=k>>1;
n=(n*n)%M;
}
return ans;
}
*/
/*
int dx4[5] = {1, -1, 0, 0 };
int dy4[5] = {0, 0, 1, -1};
int dx8[9] = { 0 , 0 , -1 , 1 , -1 , -1 , 1 , 1 } ;
int dy8[9] = { -1 , 1 , 0 , 0 , -1 , 1 , -1 , 1 } ;
int knightx[9] = { -1 , 1 , -2 , 2 , -2 , 2 , -1 , 1 } ;
int knighty[9] = { -2 , -2 , -1 , -1 , 1 , 1 , 2 , 2 } ;
bool valid( int r , int c , int x , int y ){ if( x >= 1 && x <= r && y >= 1 && y <= c ) return 1 ; return 0 ; }
*/
using namespace std;
bool arr[100000003];
vecl v;
// This is a very efficient seive of eratosthenes. Time complexity: O(nloglogn) .
// Can store 5*10^6 prime numbers below 10^8 on c++14 ideone compiler.
void seive(int n)
{
lli root=sqrt(n)+1,p,i,j;
arr[0]=arr[1]=1;
v.pb(2);
for(i=3;i<=root;i+=2)
{
if(!arr[i])
{
v.pb(i);
p=i<<1;
for( j=i*i ; j<=n ; j+=p)
arr[j]=1;
}
}
for( i=root&1?root+2:root+1 ; i<=n ; i+=2 )
if(!arr[i])
v.pb(i);
}
int main()
{
int n,i,j;
scin(n);
seive(n);
int p=v.size();
for(i=0;i<p;i++)
cout << v[i] << endl;
#ifdef HOME
cerr << "Time elapsed: " << clock() / 1000 << " ms" << endl;
#endif
return 0;
}