Hi when I am trying to submit this code on SPOJ https://www.spoj.com/problems/PRIME1/ I am getting a runtime error

#1

#include <bits/stdc++.h>
using namespace std;
const int N = 100000;
vector primes;
int p[N] = {0};
void seive()
{
for (int i = 2; i <= N; i++)
{
if (p[i] == 0)
{
primes.push_back(i);
//int s = i * i;
for (int j = i; j <= N; j += i)
{
p[j] = 1;
}
}
}
}

int main()
{

seive();
int t;
cin >> t;
while (t--)
{
	int n, m;
	cin >> m >> n;
	bool segment[n - m + 1];
	for (int i = 0; i < n - m + 1; i++)
	{
		segment[i] = 0;
	}

	//Segmented Seive Starts
	for (auto x : primes)
	{
		if (x * x > n)
		{
			break;
		}
		int start = (m / x) * x;
		//Mark all multiples of x as not primes
		if (x >= m and x <= n)
		{
			start = x * 2;
		}
		for (int i = start; i <= n; i += x)
		{
			segment[i - m] = 1;
		}

	}
	for (int i = m; i <= n; i++)
	{
		if (segment[i - m] == 0 && i != 1)
		{
			cout << i << " ";
		}
	}
	cout << endl;
}

}

#2

plz share link of your code

save at http://ide.codingblocks.com/
and then the link generated

#3

Hi,

#4

if(start<m) start+=x;
add this line before marking segment array
because if i<m then segment[i-m] will give error as you are accessing negative index

#5

Hi Actually I added that line but it is still giving runtime error.

#6

Try to make these changes:

  1. first take m then n
  2. use long long int
#7

Hi
If you notice in the above code I have taken m before n.

#8

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