poj 2105 IP Address(水题)

一、Description

Suppose you are reading byte streams from any device, representing IP addresses. Your task is to convert a 32 characters long sequence of '1s' and '0s' (bits) to a dotted decimal format. A dotted decimal format for an IP address
is form by grouping 8 bits at a time and converting the binary representation to decimal representation. Any 8 bits is a valid part of an IP address. To convert binary numbers to decimal numbers remember that both are positional numerical systems, where the
first 8 positions of the binary systems are:

27   26  25  24  23   22  21  20 

128 64  32  16  8   4   2   1 

Input

The input will have a number N (1<=N<=9) in its first line representing the number of streams to convert. N lines will follow.

Output

The output must have N lines with a doted decimal IP address. A dotted decimal IP address is formed by grouping 8 bit at the time and converting the binary representation to decimal representation.

二、题解

       今天见鬼了，碰到这么多水题。这题就是在采用什么读取输入流时纠结了一下，最后还是用了SC,然后再用字符串的性质解决了问题。

三、java代码

import java.util.Scanner;

public class Main {
	public static int transform(String s){
		int sum=0;
		if(s.charAt(0)=='1')
			sum+=128;
		if(s.charAt(1)=='1')
			sum+=64;
		if(s.charAt(2)=='1')
			sum+=32;
		if(s.charAt(3)=='1')
			sum+=16;
		if(s.charAt(4)=='1')
			sum+=8;
		if(s.charAt(5)=='1')
			sum+=4;
		if(s.charAt(6)=='1')
			sum+=2;
		if(s.charAt(7)=='1')
			sum+=1;
		return sum;
	}
    public static void main(String[] args) {
    	Scanner sc=new Scanner(System.in);
    	int n,i;
    	String s;
    	n=sc.nextInt();
    	for(i=0;i<n;i++){
    		s=sc.next();
    		System.out.println(transform(s.substring(0,8))+"."+transform(s.substring(8,16))+"."
    				+transform(s.substring(16,24))+"."+transform(s.substring(24,32)));
    	}

    }
}