-
Notifications
You must be signed in to change notification settings - Fork 0
/
Uva 686 - Goldbach's Conjecture(II).java
60 lines (56 loc) · 1.67 KB
/
Uva 686 - Goldbach's Conjecture(II).java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
package com.company.Main;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashSet;
public class Main {
static ArrayList<Integer> primes = new ArrayList<>();
static HashSet<Integer> Primes = new HashSet<>();
public static void main(String[] args) throws IOException{
// write your code here
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
String s;
SeiveOfEisten(32780);
while ((s=br.readLine())!=null&&!s.equals("0"))
{
int T = Integer.parseInt(s);
int i=0;
int howmanyCobjectures = 0;
while (primes.get(i)<=Math.ceil(T/2.0)) {
if (Primes.contains(T-primes.get(i)))
howmanyCobjectures++;
i++;
}
System.out.println(howmanyCobjectures);
}
}
static void SeiveOfEisten(int n)
{
boolean[] prime = new boolean[n+1];
for (int i=0;i<=n;i++)
prime[i] = true;
for (int factor = 2; factor*factor<=n;factor++)
{
if (prime[factor])
for (int i=factor*factor;i<=n;i+=factor)
prime[i] =false;
}
for (int i=2;i<=n;i++)
if (prime[i]) {
primes.add(i);
Primes.add(i);
}
}
public static class Pair
{
int u;
int v;
Pair(int u, int v)
{
this.u = u;
this.v = v;
}
}
}