Eratosthenes筛法 构造素数表—— Java

public class Main {
    public static void main(String[] args){
        //构造2至1779的素数表,1不是素数
        int n = 1779;
        boolean[] vis = new boolean[n+1];
        int m = (int) Math.sqrt(n+0.5);
        for(int i = 2;i <= m;i++){
            if(vis[i] == false){
                for(int j = i*i;j <= n;j += i){
                    vis[j] = true;
                }
            }
        }
    }
}