poj 1753 flip game

直接枚举

//2011-11-1
#include <iostream>
#include <cstdio>

using namespace std;

void Replace(char a[], int b[]);
int Search(int a[]);
bool Judge(int a[]);
void Flip(int b[], int k);

int main()
{
    char a[16], c;
    int b[16];
    int i = 0;
    while ((c = getchar()) != EOF && i < 16)
        if (c == 'b' || c == 'w')
        {
            a[i] = c;
            ++i;
        }
    Replace(a, b);
    int ans = Search(b);
    if (ans != -1) cout << ans << endl;
    else cout << "Impossible";

    return 0;
}

void Repeat(int n, int i[])
{
    for (int k= 15; k >= 0; --k)
    {
        i[k] = n%2;
        n /= 2;
    }
}
int Search(int a[])
{
    bool FLAG = false;
    int i[16], b[16];
    int min = 2000;
    for (int counter = 65535; counter >= 0; --counter)
    {
    for (int j = 0; j < 16; ++j)
    {
        b[j] = a[j];
        i[j] = 0;
    }
        Repeat(counter, i);
        int count = 0;
        for (int k = 0; k < 16; ++k)
            if (i[k] == 1)
            {
                Flip(b, k);
                ++count;
            }
        if (Judge(b) && count < min)
        {
            FLAG = true;
            min = count;
        }
    }
    if (FLAG) return min;
    return -1;
}
bool Judge(int a[])
{
    int sum = 0;
    for (int i = 0; i < 16; ++i)
        sum += a[i];
    if (sum == 16 || sum == 0)
        return true;
    return false;
}
void Flip(int b[], int k)
{
    b[k] = 1 - b[k];
    int i = k%4, j = k/4;
    if (i < 3) b[k+1] = 1 - b[k+1];
    if (i > 0) b[k-1] = 1 - b[k-1];
    if (j < 3) b[k+4] = 1 - b[k+4];
    if (j > 0) b[k-4] = 1 - b[k-4];
}
void Replace(char a[], int b[])
{
    for (int i = 0; i < 16; ++i)
    {
        if (a[i] == 'b')
            b[i] = 1;
        else b[i] = 0;
    }
}