【POJ 2965】 The Pilots Brothers' refrigerator

【题目链接】

           http://poj.org/problem?id=2965

【算法】

           位运算

【代码】

          

#include <algorithm>  
#include <bitset>  
#include <cctype>  
#include <cerrno>  
#include <clocale>  
#include <cmath>  
#include <complex>  
#include <cstdio>  
#include <cstdlib>  
#include <cstring>  
#include <ctime>  
#include <deque>  
#include <exception>  
#include <fstream>  
#include <functional>  
#include <limits>  
#include <list>  
#include <map>  
#include <iomanip>  
#include <ios>  
#include <iosfwd>  
#include <iostream>  
#include <istream>  
#include <ostream>  
#include <queue>  
#include <set>  
#include <sstream>  
#include <stdexcept>  
#include <streambuf>  
#include <string>  
#include <utility>  
#include <vector>  
#include <cwchar>  
#include <cwctype>  
#include <stack>  
#include <limits.h> 
using namespace std;
const int MASK = 65535;

int i,j,tmp,s,mn,p,sum;
int a[16];
char c;

inline int calc(int x,int y)
{
        int pos = 4 * x + y - 5;
        int ret = 0;
        int tmp = pos;
        while (tmp < 4 * x)
        {
                ret |= (1 << tmp);
                tmp++;        
        }    
        tmp = pos;
        while (tmp >= 4 * x - 4)
        {
                ret |= (1 << tmp);
                tmp--;
        }
        tmp = pos; 
        while (tmp < 16)
        {
                ret |= (1 << tmp);
                tmp += 4;
        }
        tmp = pos;
        while (tmp >= y - 1)
        {
                ret |= (1 << tmp);
                tmp -= 4;
        }
        return ret;
}
 
int main() 
{
        
        for (i = 1; i <= 4; i++)
        {
                for (j = 1; j <= 4; j++)
                {
                        a[4*i+j-5] = calc(i,j);
                }
        }
        for (i = 0; i < 16; i++)
        {
                scanf("%c",&c);
              if (c == '-')    s |= (1 << i);        
                if (i % 4 == 3) scanf("%c",&c);
        }
        mn = MASK;
        for (i = 0; i <= MASK; i++)
        {
                tmp = s; sum = 0;
                for (j = 0; j < 16; j++)
                {
                        if (i & (1 << j))
                        {
                                sum++;    
                                tmp ^= a[j];
                        }
                }    
                if (tmp == MASK && sum < mn)
                {
                        mn = sum;
                        p = i;
                }
        }
        printf("%d
",mn);
        for (i = 0; i < 16; i++)
        {
                if (p & (1 << i))
                        printf("%d %d
",i/4+1,i%4+1);        
        }
                
        return 0;
    
}