hihoCoder#1048 状态压缩·二

原题地址

位运算的状态压缩太操蛋了，很容易出错。。。又是数组没开够导致诡异现象（明明某个值是1，莫名其妙就变成0了），害我debug一整天！fuck

代码：

#include <iostream>
#include <cstring>

using namespace std;

#define MAX_N 1024
#define MAX_M 8
#define MAX_S 4096
#define MOD 1000000007

int f[MAX_N][MAX_M][MAX_S];
int N, M;

bool freep(int s, int o) {
  return !(s & (1 << o));
}

int mark(int s, int o) {
  return s |= (1 << o);
}

int mark(int s, int o1, int o2) {
  return mark(s, o1) | mark(s, o2);
}

int main() {
  cin >> N >> M;
  memset(f, 0, sizeof(f));

  for (int i = 1; i <= N; i++) {
    for (int s = 0; s < (1 << (2 * M + 1)); s++)
      f[i][M + 1][s] = 1;
  }
  for (int j = 1; j <= M; j++) {
    for (int s = 0; s < (1 << (2 * M + 1)); s++)
      f[N + 1][j][s] = 1;
  }

  for (int i = N; i >= 1; i--) {
    for (int j = M; j >= 1; j--) {
      for (int k = (1 << (2 * M)) - 1; k >= 0; k--) {
        int s = k << 1;
        // pass
        if (!freep(s, j)) {
          if (j < M)
            f[i][j][s] = f[i][j + 1][s];
          if (j == M)
            f[i][j][s] = f[i + 1][1][(s >> M) >> 1 << 1];
        }
        if (freep(s, j)) {
          // impossible
          if ((j == M || !freep(s, j + 1)) && (i == N || !freep(s, j + M)))
            f[i][j][s] = 0;
          // right
          if (j < M && freep(s, j + 1) && (i == N || !freep(s, j + M)))
            f[i][j][s] += f[i][j][mark(s, j, j + 1)];
          // down
          if (i < N && freep(s, j + M) && (j == M || !freep(s, j + 1)))
            f[i][j][s] += f[i][j][mark(s, j, j + M)];
          // right & down
          if (j < M && freep(s, j + 1) && i < N && freep(s, j + M))
            f[i][j][s] = (f[i][j][mark(s, j, j + 1)] + f[i][j][mark(s, j, j + M)]) % MOD;
        }
      }
    }
  }

  cout << f[1][1][0] << endl;

  return 0;
}