CCF-CIDR合并 java代码（仅供参考）修改

题目：

试题编号： 201812-3
试题名称： CIDR合并
时间限制： 1.0s
内存限制： 512.0MB
问题描述：

 

样例输入

2
1
2

样例输出

扫描二维码关注公众号，回复： 7038191 查看本文章

1.0.0.0/8
2.0.0.0/8

样例输入

2
10/9
10.128/9

样例输出

10.0.0.0/8

样例输入

2
0/1
128/1

样例输出

0.0.0.0/0

经过思考，我运用java语言初步实现了CIDR合并的任务，一共包含两个类，一个类是ip地址，一个是主类，直接上代码

IPaddress类：

public class IPaddress {

 

String string = null;
Integer len = 0;

 

public IPaddress(String temp, int lenth) {
this.string = temp;
this.len = lenth;
}

 

public String getaddress() {
return this.string;
}

 

public int getlength() {
return this.len;
}

 

}

接下来是MAIN类，其中DealTheIPaddress(String)方法是将输入的不是标准IP地址转换成标准的保存在iPaddresses这个list中；

　　FTToBinary(List<IPaddress>)是将十进制的ip地址转换成二进制的ip地址保存到binaryIPaddresses这个list中；

　　FSmToBigMerge(List<IPaddress>)这个方法是从小到大合并，作用题目中有描述；

　　SameLevelMerge(List<IPaddress>)是同级合并，作用题目中有描述；

　　最后是main方法，起到在控制台输入数据，调用方法的作用。

MAIN类：

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Scanner;

 

 

public class MAIN {

 

private static List<IPaddress> iPaddresses = new ArrayList<IPaddress>();
private static List<IPaddress> binaryIPaddresses = new ArrayList<IPaddress>();

 

public static void main(String[] args) {


Scanner scanner = new Scanner(System.in);
System.out.println("Input num");
int num = scanner.nextInt();
MAIN main = new MAIN();

 

for (int i = 0; i < num; i++) {
String iPString = scanner.next();
IPaddress temPaddress = main.DealTheIPaddress(iPString);
iPaddresses.add(temPaddress);
System.out.println(temPaddress.string + " len " + temPaddress.len);
}


Collections.sort(iPaddresses, new Comparator<Object>() {// 排序，先对ip地址大小进行判定，然后相同的条件下考虑前缀长度

 

@Override // 重写，因为题目中要求是先对ip地址排序，然后考虑前缀长度
public int compare(Object o1, Object o2) {

IPaddress s1 = (IPaddress) o1;
IPaddress s2 = (IPaddress) o2;

 

String[] chartString1 = s1.string.split("\\.|/");
String[] chartString2 = s2.string.split("\\.|/");


int[] num1 = new int[4];// 存储将ip地址从string转换成int类型的数据
int[] num2 = new int[4];

 

for (int i = 0; i < 4; i++) {
num1[i] = Integer.parseInt(chartString1[i]);
num2[i] = Integer.parseInt(chartString2[i]);
}

for (int i = 0; i < 4; i++) {

if (num1[i] > num2[i]) {
return 1;
}

if (num1[i] < num2[i]) {
return -1;
}


}
if (s1.len > s2.len) {
return 1;
}

if (s1.len < s2.len) {
return -1;
}

return 0;

 

}

});

 

main.FTToBinary(iPaddresses);

 

// 从小到大合并

 

main.FSmToBigMerge(iPaddresses);


// 同级合并


main.SameLevelMerge(iPaddresses);


for (int i = 0; i < iPaddresses.size(); i++) {
System.out.println(iPaddresses.get(i).string + "/" + iPaddresses.get(i).len);
}


scanner.close();

}

 

public IPaddress DealTheIPaddress(String iPString) {// 将收到的不完全的ip地址转换成标准的ip地址


IPaddress killqueen = null;
String[] chartStrings = iPString.split("\\.|/");

System.out.println("length " + chartStrings.length);
if (chartStrings.length < 5) {// 处理不是标准形态的ip地址
if (iPString.contains("/")) {// 包含前缀长度的非标准形态的ip地址

int length = Integer.parseInt(chartStrings[chartStrings.length - 1]);
String tempString = chartStrings[0];


for (int i = 1; i < chartStrings.length - 1; i++) {
tempString = tempString + "." + chartStrings[i];
}


for (int j = chartStrings.length - 1; j < 4; j++) {
tempString = tempString + ".0";
}


killqueen = new IPaddress(tempString, length);


} else {// 处理不包含前缀长度的ip地址


int lengh = chartStrings.length * 8;
String tempString = chartStrings[0];
for (int i = 1; i < chartStrings.length; i++) {
tempString = tempString + "." + chartStrings[i];


}


for (int j = chartStrings.length; j < 4; j++) {
tempString = tempString + ".0";
}


killqueen = new IPaddress(tempString, lengh);


}

} else {// 标准形态的ip地址
String tempString = chartStrings[0];


for (int i = 1; i < chartStrings.length - 1; i++) {
tempString = tempString + "." + chartStrings[i];
}


killqueen = new IPaddress(tempString, Integer.parseInt(chartStrings[chartStrings.length - 1]));
return killqueen;
}
return killqueen;
}

 

public void FTToBinary(List<IPaddress> iPaddresses) {// 将ip地址从十进制转换成二进制

 

for (int i = 0; i < iPaddresses.size(); i++) {

IPaddress killqueen = null;
String[] s1 = iPaddresses.get(i).string.split("\\.|/");
int[] num = new int[5];
String[] binStrings = new String[5];
String tempString = null;

for (int j = 0; j < s1.length; j++) {
num[j] = Integer.parseInt(s1[j]);
binStrings[j] = Integer.toBinaryString(num[j]);
}

 

// 还需要将ip地址补全，不足8位要补齐
for (int j = 0; j < binStrings.length - 1; j++) {
String tempString2 = "0";
if (binStrings[j].length() < 8) {
for (int k = 1; k < 8 - binStrings[j].length(); k++) {
tempString2 = tempString2 + "0";
}


tempString2 = tempString2 + binStrings[j];
binStrings[j] = tempString2;


}

}

 

tempString = binStrings[0];


for (int j = 1; j < binStrings.length - 1; j++) {
tempString = tempString + "." + binStrings[j];
}

 

killqueen = new IPaddress(tempString, iPaddresses.get(i).len);
binaryIPaddresses.add(killqueen);


}
}


public void FSmToBigMerge(List<IPaddress> iPaddresses) {

 

for (int i = 0; i < binaryIPaddresses.size() - 1; i++) {
boolean same = true;
String[] s1 = new String[4];
String[] s2 = new String[4];
String string1 = null;
String string2 = null;
char[] char1 = new char[32];
char[] char2 = new char[32];

 

s1 = binaryIPaddresses.get(i).string.split("\\.");
s2 = binaryIPaddresses.get(i + 1).string.split("\\.");

 

string1 = s1[0];
string2 = s2[0];

 

for (int j = 1; j < s1.length; j++) {
string1 = string1 + s1[j];
string2 = string2 + s2[j];
}

 

for (int j = 0; j < 32; j++) {
char1[j] = string1.charAt(j);

char2[j] = string2.charAt(j);
}

 

for (int j = 0; j < binaryIPaddresses.get(i).len; j++) {
if (char1[j] != char2[j]) {
same = false;
break;
}


}


if (!same) {
continue;
}


if (same) {
binaryIPaddresses.remove(i + 1);
iPaddresses.remove(i + 1);
i--;
continue;
}

 

}
}

 

public void SameLevelMerge(List<IPaddress> iPaddresses) {

 

for (int i = 0; i < binaryIPaddresses.size() - 1; i++) {
String[] s1 = new String[4];
String[] s2 = new String[4];
String string1 = null;
String string2 = null;
char[] char1 = new char[32];
char[] char2 = new char[32];
IPaddress newip = null;
IPaddress newip1 = null;
boolean couldmerge = true;

 

if (binaryIPaddresses.get(i).len == binaryIPaddresses.get(i + 1).len) {


s1 = binaryIPaddresses.get(i).string.split("\\.");
s2 = binaryIPaddresses.get(i + 1).string.split("\\.");

string1 = s1[0];
string2 = s2[0];

 

for (int j = 1; j < s1.length; j++) {
string1 = string1 + s1[j];
string2 = string2 + s2[j];
}

 

for (int j = 0; j < string1.length(); j++) {
char1[j] = string1.charAt(j);
char2[j] = string2.charAt(j);
}

 

if (char1[binaryIPaddresses.get(i).len - 1] == '0') {
newip = new IPaddress(binaryIPaddresses.get(i).string, binaryIPaddresses.get(i).len - 1);
newip1 = new IPaddress(iPaddresses.get(i).string, iPaddresses.get(i).getlength() - 1);
} else {
continue;
}

 

for (int j = 0; j < newip.len; j++) {
if (char1[j] != char2[j]) {
couldmerge = false;
}
}

 

if (!couldmerge) {
continue;
}

 

if (couldmerge) {
binaryIPaddresses.remove(i + 1);// 先移除i+1，因为如果先移除i，那么后面的下标会自动-1，那么后面移除的i+1其实是原来的i+2
binaryIPaddresses.remove(i);
binaryIPaddresses.add(i, newip);
iPaddresses.remove(i + 1);
iPaddresses.remove(i);
iPaddresses.add(i, newip1);
i--;
}

 

} else {
continue;
}
}
}

}