The Fun Number System
| Time Limit: 1000MS |
| Memory Limit: 10000K |
| Total Submissions: 8549 |
| Accepted: 2797 |
Description
In a k bit 2's complement number, where the bits are indexed from 0 to k-1, the weight of the most significant bit (i.e., in position k-1), is -2^(k-1), and the weight of a bit in any position i (0 ≤ i < k-1) is 2^i. For example, a 3 bit number 101 is -2^2 + 0 + 2^0 = -3. A negatively weighted bit is called a negabit (such as the most significant bit in a 2's complement number), and a positively weighted bit is called a posibit.
A Fun number system is a positional binary number system, where each bit can be either a negabit, or a posibit. For example consider a 3-bit fun number system Fun3, where bits in positions 0, and 2 are posibits, and the bit in position 1 is a negabit. (110)Fun3 is evaluated as 2^2-2^1 + 0 = 3. Now you are going to have fun with the Fun number systems! You are given the description of a k-bit Fun number system Funk, and an integer N (possibly negative. You should determine the k bits of a representation of N in Funk, or report that it is not possible to represent the given N in the given Funk. For example, a representation of -1 in the Fun3 number system (defined above), is 011 (evaluated as 0 - 2^1 + 2^0), and
representing 6 in Fun3 is impossible.
Input
The first line of the input file contains a single integer t (1 ≤ t ≤ 10), the number of test cases, followed by the input data for each test case. Each test case is given in three consecutive lines. In the first line there is a positive integer k (1 ≤ k ≤ 64). In the second line of a test data there is a string of length k, composed only of letters n, and p, describing the Fun number system for that test data, where each n (p) indicates that the bit in that position is a negabit (posibit).
The third line of each test data contains an integer N (-2^63 ≤ N < 2^63), the number to be represented in the Funk number
system by your program.
Output
For each test data, you should print one line containing either a k-bit string representing the given number N in the Funk number system, or the word Impossible, when it is impossible to represent the given number.
Sample Input
2 3 pnp 6 4 ppnn 10
Sample Output
Impossible 1110
Source
Tehran 2002, First Iran Nationwide Internet Programming Contest
是个好题，不过没想出来怎么做，跟数的补码有关
code
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <ctime>
#include <cassert>
#include <iostream>
#include <sstream>
#include <fstream>
#include <map>
#include <set>
#include <vector>
#include <queue>
#include <algorithm>
#include <iomanip>
using namespace std;
__int64 maxnum,minnum;
__int64 n;
char s[100];
int main()
{
char str[100];
int t,len;
long long flag;
scanf("%d",&t);
while(t--)
{
scanf("%d",&len);
scanf("%s",str);
scanf("%I64d",&n);
maxnum=0;
minnum=0;
for(int i=0; i<len; i++)
{
if(str[i]=='p') maxnum=maxnum*2+1,minnum=minnum*2;
else maxnum=maxnum*2,minnum=minnum*2-1;
}
memset(s,0,sizeof(s));
if((n<minnum&&minnum<=0)||(n>maxnum&&maxnum>=0)) printf("Impossible\n");
else
{
for(int i=len-1; i>=0; i--)
{
flag=0;
if(n&1)
{
s[i]='1';
if(str[i]=='n')flag=1;
}
else s[i]='0';
n=n>>1;
// printf("%d\n",n);
if(flag) n++;
// printf("%d\n",n);
}
puts(s);
}
}
return 0;
}