题解 | #识别有效的IP地址和掩码并进行分类统计#

我是真的无力吐槽这种题目，讲的不清不楚的！！！！！
注意点：
-1 255.255.255.255 不算子网掩码（调试1小时才发现）
-2 题目说的是，错误IP地址或错误掩码，就是这条输入错误了意思，
-3 说句实话，做这种写的又臭又长看的都恶心的代码不如不写

import java.security.PublicKey;
import java.util.*;
/*输入：
10.70.44.68~255.254.255.0
1.0.0.1~255.0.0.0
192.168.0.2~255.255.255.0
19..0.~255.255.255.0
复制
输出：
1 0 1 0 0 2 1
*/


public class Main {
    static int A = 0, B = 0, C = 0, D = 0, E = 0, error = 0, pri = 0;

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        while (scanner.hasNextLine()) {
            String s = scanner.nextLine();
            String[] split = s.split("~");
            if (split.length != 2) {
                error++;
                continue;
            }
            String left = split[0];
            String right = split[1];
            help(left, right);
           // System.out.println(A + " " + B + " " + C + " " + D + " " + E + " " + error + " " + pri);
        }
        System.out.println(A + " " + B + " " + C + " " + D + " " + E + " " + error + " " + pri);

    }

    private static void help(String left, String right) {
        String[] ips = left.split("\\.");
        String[] ip_2s = right.split("\\.");
        if (ips.length != 4 || ip_2s.length != 4) {
            error++;
            return;
        }
        int ip0 = Integer.parseInt(ips[0]);
        int ip1 = Integer.parseInt(ips[1]);
        int ip2 = Integer.parseInt(ips[2]);
        int ip3 = Integer.parseInt(ips[3]);
        int ip_0 = Integer.parseInt(ip_2s[0]);
        int ip_1 = Integer.parseInt(ip_2s[1]);
        int ip_2 = Integer.parseInt(ip_2s[2]);
        int ip_3 = Integer.parseInt(ip_2s[3]);
        if (ip0 > 255 || ip1 > 255 || ip2 > 255 || ip3 > 255 || ip_0 > 255 || ip_1 > 255 || ip_2 > 255 || ip_3 > 255) {
            error++;
            return;
        }
        if (!judge(ip_0, ip_1, ip_2, ip_3)) {
            error++;
            return;
        }
        if (ip0 > 0 && ip0 < 127) {
            A++;
            if (ip0 == 10) {
                pri++;
            }
            return;
        } else if (ip0 > 127 && ip0 < 192) {
            B++;
            if (ip0 == 172 && ip1 >= 16 && ip1 <= 31) {
                pri++;
            }
            return;
        } else if (ip0 >= 192 && ip0 <= 223) {
            C++;
            if (ip0 == 192 && ip1 == 168) {
                pri++;
            }
        } else if (ip0 >= 224 && ip0 <= 239) {
            D++;
        } else if (ip0 >= 240 && ip0 <= 255) {
            E++;
        }


    }

    private static boolean judge(int ip_0, int ip_1, int ip_2, int ip_3) {
        if (ip_0 == 255 && ip_1 == 255 && ip_2 == 255 && ip_3 == 255) {
            return false;
        }
        String i_0 = Integer.toBinaryString(ip_0);
        String i_1 = Integer.toBinaryString(ip_1);
        String i_2 = Integer.toBinaryString(ip_2);
        String i_3 = Integer.toBinaryString(ip_3);
        while (i_1.length() < 8) {
            i_1 = "0" + i_1;
        }
        while (i_2.length() < 8) {
            i_2 = "0" + i_2;
        }
        while (i_3.length() < 8) {
            i_3 = "0" + i_3;
        }
        char[] chars = (i_0 + i_1 + i_2 + i_3).toCharArray();
        boolean flage = false;
        for (int i = 0; i < chars.length; i++) {
            if (chars[i] == '0') {
                flage = true;
            }
            if (flage == true && chars[i] == '1') {
                return false;
            }

        }

        return true;
    }

}