Prime visits check the mistake

#1

#include
using namespace std;
#define ll long long
void prime_sieve(int *p)
{
for(int i=3;i<=1000000;i+=2)
{
p[i]=1;
}

for(int i=3;i<=1000000;i+=2)
{
	if(p[i]==1)
	{
		for(ll j=i*i;j<=1000000;j++)
		{
			p[j]=0;
		}
	}
}
p[2]=1;
p[1]=p[0]=0;

}
int main() {

int p[1000000]={0};
prime_sieve(p);

int csum[1000000]={0};

for(int i=1;i<1000000;i++)
{
	csum[i]=csum[i-1]+p[i];
}

int q;
cin>>q;

while(q--)
{
	int a,b;
	cin>>a>>b;

	cout<<csum[b]-csum[a-1]<<endl;
}
return 0;

}

#2

@arsh_goyal Please change your prime_sieve function to this

void prime_sieve(int* p){
for(ll i=3;i<=1000000;i+=2){
p[i]=1;
}
for(ll i=3;i<=1000000;i+=2){
if(p[i]){
for(ll j=i*i;j<=1000000;j+=i){
p[j]=0;
}
}
}
p[2]=1;
}

and increase size of your p[] to p[1000005]

#3

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