【很简洁】两行代码判断IP地址归属地是洲内还是洲外

支持多种语言

原理：根据IPv4地址首位判断是否属于亚太地区(APNIC)管辖

说明：仅限估计，有些情况下不是特别准确，建议用于服务器防火墙过滤等场合

Java(第一种):

String ip="114.5.1.4";

static final String N=new java.math.BigInteger("1ljkvi5u19606s37nxu2ao4bjh5ld594gocu1j05ftpgykadq8",36).toString(2);
boolean inAsia=N.charAt(Integer.parseInt(ip.substring(0,ip.indexOf("."))))=='1';//true

Java(第二种):

//According to https://www.iana.org/assignments/ipv4-address-space/ipv4-address-space.xhtml
static long[] co=new long[]{0x402200100930403cl,0x523ffffl,0x400024010110b00l,0x30303fl<<8};
public static boolean inAsia(String ip){
    int c=Integer.parseInt(ip.substring(0,ip.indexOf(".")));
    return (co[c>>6]&(1l<<63-(63&c)))!=0;
}
public void demo(){
    while(true)System.out.println(inAsia(new java.util.Scanner(System.in).nextLine())?"在亚太":"在洲外");
}

C/C++:

long long co[4]={0x402200100930403cll,0x523ffffll,0x400024010110b00ll,0x30303fll<<8};
char inAsia(const char* x){
    for(int c=*x^'0',i=0;x[++i]^'.';c=(c<<3)+(c<<1)+(x[i]^'0'));
    return 1&(co[c>>6]>>63-(63&c));
}
int main(){
    for(char q[16];scanf("%s",q),1;puts({"在洲外","在亚太"}[inAsia(q)]));
}