primesearch.java

来自「服务器模块主要负责分配计算任务」· Java 代码 · 共 46 行

package primecruncher;
import net.jxta.peergroup.*;
import net.jxta.exception.*;
import java.util.*;

public class PrimeSearch{
    public static int numPrimes(int from,int to){
        return findPrimes(from,to).length;
    }
/*****************************************************************/
    public static int[] findPrimes(int from,int to){
        if(from > to){
            throw new IllegalArgumentException("First number must be smaller than the second.");
        }
        int[] list;
        list=new int[to-from+1];
        for(int i=0;i<list.length;i++){
            list[i]=from++;
        }
        int maxDiv=(int)Math.sqrt(to);
        int[] mark=new int[list.length];
        for(int i=0;i<list.length;i++){
            for(int z=2;z<=maxDiv;z++){
                if(list[i]!=z&&(list[i]%z==0)){
                    mark[i]=1;
                }
            }
        }
        int primes=0;
        for(int i=0;i<mark.length;i++){
            if(mark[i]==0){
                primes++;
            }
        }
        int[] ret=new int[primes];
        int curs=0;
        for(int i=0;i<mark.length;i++){
            if(mark[i]==0){
                ret[curs]=list[i];
                curs++;
            }
        }
        return ret;
    }
}