Problem PRIME1 from SPOJ

PRIME1.cpp

@@ -0,0 +1,66 @@
+// Problem: PRIME1 from SPOJ
+
+#include <bits/stdc++.h>
+using namespace std;
+
+vector<int> primes;
+bool isPrime[40001]; // use this to answer queries if n <= 40000
+
+void sieve(){
+	int i,j;
+
+	for(i=1;i<=40000;i++)isPrime[i] = true;
+	isPrime[1] = false;
+
+	for(i=2;i<=200;i++){
+		if(isPrime[i]){
+			primes.push_back(i);
+			for(j=2*i;j<=40000;j+=i)isPrime[j] = false;
+		}
+	}
+
+	for(i=201;i<=40000;i++)if(isPrime[i])primes.push_back(i);
+
+	return ;
+}
+
+void solve(){
+	int m,n,i,c;
+	cin>>m>>n;
+
+	bool prime[n-m+1];
+	for(i=0;i<n-m+1;i++)prime[i] = true;
+
+	for(i=0;i<primes.size();i++){
+		c = m%primes[i];
+		if(c!=0)c = primes[i]-c;
+
+		while(c<n-m+1){
+			prime[c] = false;
+			c+=primes[i];
+		}
+	}
+
+	for(i=0;i<n-m+1;i++){
+		if(m+i<=40000){
+			if(isPrime[m+i])cout<<(m+i)<<"\n";
+		}
+		else{
+			if(prime[i])cout<<(m+i)<<"\n";
+		}
+	}
+
+	cout<<"\n";
+	return ;
+}
+
+int main(){
+	int t;
+	cin>>t;
+
+	sieve();
+
+	while(t--){
+		solve();
+	}
+}