题解 | #识别有效的IP地址和掩码并进行分类统计#

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        List<String> stringList = new ArrayList<>();
        while (in.hasNext()) {
            stringList.add(in.next());
        }
        int[] result = new int[7];
        stringList.stream().forEach(s -> {
            String[] str = s.split("~");
            if (!checkIpValid(str[0])) {
                result[5]++;
                return;
            }
            if (str[0].matches("([1-9]|[1-9]\\d|1[0-1]\\d|12[0-6])(\\.(\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])){3}")) {
                if (!checkValid(str[1])) {
                    result[5]++;
                    return;
                }
                if (str[0].matches("10(\\.(\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])){3}")) {
                    result[6]++;
                }
                result[0]++;
            } else if(str[0].matches("(12[8-9]|1[3-8]\\d|19[0-1])(\\.(\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])){3}")) {
                if (!checkValid(str[1])) {
                    result[5]++;
                    return;
                }
                if (str[0].matches("172\\.(1[0-6])|(2\\d)|(3[0-1])(\\.(\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])){2}")) {
                    result[6]++;
                }
                result[1]++;
            } else if(str[0].matches("(19[2-9]|2[0-1]\\d|22[0-3])(\\.(\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])){3}")) {
                if (!checkValid(str[1])) {
                    result[5]++;
                    return;
                }
                if (str[0].matches("192\\.168(\\.(\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])){2}")) {
                    result[6]++;
                }
                result[2]++;
            } else if(str[0].matches("(22[4-9]|23\\d)(\\.(\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])){3}")) {
                if (!checkValid(str[1])) {
                    result[5]++;
                    return;
                }
                result[3]++;
            } else if(str[0].matches("(24\\d|25[0-5])(\\.(\\d|[1-9]\\d|1\\d\\d|2[0-4]\\d|25[0-5])){3}")) {
                if (!checkValid(str[1])) {
                    result[5]++;
                    return;
                }
                result[4]++;
            }
        });
        for (int i : result) {
            System.out.print(i + " ");
        }
    }

    private static boolean checkIpValid(String s) {
        String[] strings = s.split("\\.");
        if (strings.length < 4) {
            return false;
        }
        List<String> stringList = Arrays.asList(strings);
        if (stringList.contains("")) {
            return false;
        }
        return true;
    }

    private static boolean checkValid(String s) {
        String[] strings = s.split("\\.");
        if (strings.length < 4) {
            return false;
        }
        List<String> stringList = Arrays.asList(strings);
        if (stringList.contains("")) {
            return false;
        }
        if (4 == stringList.stream().filter(s1 -> s1.equals("255")).count()) {
            return false;
        }
        if (4 == stringList.stream().filter(s1 -> s1.equals("0")).count()) {
            return false;
        }
        for (int i = 0; i < 4; i++) {
            if (strings[i].equals("0")) {
                continue;
            }
            if (i != 0 && !strings[i-1].equals("255")) {
                return false;
            }
            int n = Integer.parseInt(strings[i]);
            for (int j = 7; j >= 0 ; j--) {
                n -= Math.pow(2,j);
                if (n == 0) {
                    break;
                }
                if (n < 0) {
                    return false;
                }
            }
        }
        return true;
    }
}