poj 2105 大数

IP Address

Time Limit: 1000MS Memory Limit: 30000KTotal Submissions: 19666 Accepted: 11366

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.

Sample Input

400000000000000000000000000000000 00000011100000001111111111111111 11001011100001001110010110000000 01010000000100000000000000000001 

Sample Output

0.0.0.03.128.255.255203.132.229.12880.16.0.1

就是每八位二进制数数字变成一个整数

#include<stdio.h>#include<string.h>#include<algorithm>using namespace std;char str[40];int pow(int x,int y){    int ans=2;    for(int i=1;i<y;i++)        ans*=2;    if(y==0)        ans=1;    return ans;}int main(){    int T;    scanf("%d",&T);    while(T--)    {        int a=0,b=0,c=0,d=0;        scanf("%s",str);        for(int i=7;i>=0;i--)            if(str[i]=='1')                a+=pow(2,7-i);        for(int i=15;i>=8;i--)            if(str[i]=='1')                b+=pow(2,15-i);        for(int i=23;i>=16;i--)            if(str[i]=='1')                c+=pow(2,23-i);        for(int i=31;i>=24;i--)            if(str[i]=='1')                d+=pow(2,31-i);        printf("%d.%d.%d.%d\n",a,b,c,d);    }    return 0;}