Finding prime numbers | LeetCode

Output all prime numbers up to a specified integer n.

void prime_sieve(int n, bool prime[]) {

  prime[0] = false;

  prime[1] = false;

  int i;

  for (i = 2; i <= n; i++)

    prime[i] = true;

  int limit = sqrt(n);

  for (i = 2; i <= limit; i++) {

    if (prime[i]) {

      for (int j = i * i; j <= n; j += i)

        prime[j] = false;

    }

  }

}

http://yuanhsh.iteye.com/blog/2186379

1. public List<Integer> findPrimeNumbers(int n) {   
2.     boolean[] isPrime = new boolean[n+1];  
3.     Arrays.fill(isPrime, 2, n+1, true);  
4.     for(int i=2; i*i <= n; i++) {  
5.         if(isPrime[i]) {  
6.             for(int j = i; i*j <= n; j++) {  
7.                 isPrime[i*j] = false;  
8.             }  
9.         }  
10.     }  
11.     // output all prime numbers  
12.     List<Integer> result = new ArrayList<>();  
13.     for(int i=0; i<=n; i++) {  
14.         if(isPrime[i]) {  
15.             result.add(i);  
16.         }  
17.     }  
18.     return result;  
19. }

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