SPOJ-Prime Generator

general
, ,
1

Hey i was trying SPOJ prime-generator problem and i have written my code for it and it gives correct output but SPOJ still showing that answer is wrong.
My code is below please tell why my code is wrong

#include 
using namespace std;
int t,i,j;
long long m,n;
int primegenerator(long long x);
int main()
{
    cin >> t;
    for(i=0;i> m >> n;
        for(j=m;j<=n;j++)
        {
            primegenerator(j);
        }
    }
    return 0;
}
int primegenerator(long long x)
{
    int k;
    for(k=2;k<=sqrt(x);k++)
    {
        if(x%k==0)
            return 0;
    }
    cout << x << endl;
}
2

optimize the code in primegenerator() function, by using this:

if(x%2==0)
return 0;
else{
for(int i=3;i*i<=x;i=i+2){
if(x%i==0)
return 0;
}
}

you can also use sieve of eratosthenes for finding primes, fast and efficient:

my code link: BDUVbj - Online C++0x Compiler & Debugging Tool - Ideone.com

link for sieve of eratosthenes: Sieve of Eratosthenes - GeeksforGeeks

1 Like
3

@neilit1992
Your code link is not visible.
Please give a link which i can see don’t make it private.

1 Like
4

Code link was private, made it public, check it now.

1 Like
5

/*
* spoj3.c
*
* Created on: 19-Feb-2016
* Author: Neil
/
#include<stdio.h>
#include<string.h>
int prime[32001];
int p[100001];
void sieve()
{
prime[1]=1;
int i,j;
for(i=2;ii<=32000;i++)
if(!prime[i])
for(j=2*i;j<=32000;j+=i)
prime[j]=1;

}

int main()
{
int i,j,t,m,n,v;
sieve();

scanf("%d",&t);
while(t--){
scanf("%d%d",&m,&n);
if(m<2)
m=2;

memset(p,0,sizeof(p));
for(i=2; i*i<=n; i++)
if(!prime[i])
{
v=((m-1)/i+1)*i;
for(j=v==i?i<<1:v; j<=n; j+=i)
p[j-m]=1;
}
for(i=0; i<=n-m; i++)
if(!p[i])
printf("%d\n",i+m);
printf("\n");
}
return 0;
}
6

Dude do not post solution,Instead of that give some hints only.

1 Like