题解 | #判断两个IP是否属于同一子网#

const rl = require("readline").createInterface({ input: process.stdin });
var iter = rl[Symbol.asyncIterator]();
const readline = async () => (await iter.next()).value;

void (async function () {
    // Write your code here
    while ((mask = await readline())) {
        let ip1 = await readline();
        let ip2 = await readline();
        console.log(Func(mask, ip1, ip2));
    }

    function Func(mask, ip1, ip2) {
        let regIp =
        /^(\d{1,2}|1\d{2}|2[0-4][0-9]|25[0-5])\.(\d{1,2}|1\d{2}|2[0-4][0-9]|25[0-5])\.(\d{1,2}|1\d{2}|2[0-4][0-9]|25[0-5])\.(\d{1,2}|1\d{2}|2[0-4][0-9]|25[0-5])$/;
        let regMask =
        /^((255|254|252|248|240|224|192|128)\.0\.0\.0|255\.(255|254|252|248|240|224|192|128|0)\.0\.0|255\.255\.(255|254|252|248|240|224|192|128|0)\.0|255\.255\.255\.(254|252|248|240|224|192|128|0))$/;
        if(regMask.test(mask) && regIp.test(ip1) && regIp.test(ip2)){
            let arrMask = ErJinZzhi(mask);
            let arrIp1 = ErJinZzhi(ip1);
            let arrIp2 = ErJinZzhi(ip2);
            let temp1=[], temp2=[];
            for(let i=0; i<arrMask.length; i++){
                temp1.push(arrMask[i] & arrIp1[i]);
                temp2.push(arrMask[i] & arrIp2[i]);
            }
            if(temp1.join('.') == temp2.join('.')){
                return 0;
            }else{
                return 2;
            }
        }else{
            return 1;
        }
    }

    //将IP或掩码转换为10进制（便于后续做与运算）
    function ErJinZzhi(str){
        let arr = str.split('.');
        return arr.map(n => parseInt(n));
    }
})();