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C++ Program to Generate Prime Numbers Between a Given Range Using the Sieve of Sundaram
This is C++ program to implement Sieve of Sundaram to Generate Prime Numbers Between Given Range. This algorithm was discovered in 1934 by Sundaram.
Algorithm
Begin
printPrimes(n)
Here we find out primes
smaller than n, we reduce n-2 to half. We call it New.
New = (n-2)/2;
Create an array marked[n] that is going
to be used to separate numbers of the form i+j+2ij from
others where 1 <= i <= j
Initialize all entries of marked[] as false.
Mark all numbers of the form i + j + 2ij as true
where 1 <= i <= j
for i=1 to New
a) j = i;
b) Loop While (i + j + 2*i*j) 2, then print 2 as first prime.
Remaining primes are of the form 2i + 1 where i is
index of NOT marked numbers. So print 2i + 1 for all i
such that marked[i] is false.
EndExample Code
#include <bits/stdc++.h>
using namespace std;
int SieveOfSundaram(int m) {
int N= (m-2)/2;
bool marked[N + 1];
memset(marked, false, sizeof(marked));
for (int i=1; i<=N; i++)
for (int j=i; (i + j + 2*i*j) <= N; j++)
marked[i + j + 2*i*j] = true;
if (m > 2)
cout << 2 << " ";
for (int i=1; i<=N; i++)
if (marked[i] == false)
cout << 2*i + 1 << " ";
}
int main(void) {
int m = 10;
SieveOfSundaram(m);
return 0;
}Output
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Updated on: 30-Jul-2019
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