IP判断 （Java代码）

解题思路:





注意事项:





参考代码:

import java.util.Scanner;

public class A1116 {

public static void main(String args[]) {

Scanner sc = new Scanner(System.in);

loop: do {

String s = sc.next();

int n = 0;

char a[] = new char[s.length()];

for (int i = 0; i < a.length; i++) {

a[i] = s.charAt(i);

}

int b = 0;

int c = 0;

for (int i = 0; i < a.length; i++) {

int sum = 0;

if (a[i] == '.') {

c = i;

for (int x = b; x < c; x++) {

if (a[x] == '.') {

continue;

}

if (a[x] >= '0' && a[x] <= '9') {

sum = sum * 10 + a[x]-48;

} else {

System.out.println("N");

continue loop;

}

}

b = c;

}

if(a[i]!='.')

continue;

if (sum <= 255) {

n++;

}

if (sum >= 255) {

System.out.println("N");

continue loop;

}

if (n == 3) {

sum = 0;

for (int x = c; x < a.length; x++) {

if (a[x] == '.') {

continue;

}

if (a[x] >= '0' && a[x] <= '9') {

sum = sum * 10 + a[x]-48;

} else {

System.out.println("N");

continue loop;

}

}

if (sum <= 255)

System.out.println("Y");

if (sum >= 255) {

System.out.println("N");

continue loop;

}

}

}

} while (sc.hasNext());

}

}