[CQOI2014]和谐矩阵

题解：

bitset优化高斯校园

无关变量为1

#include <bits/stdc++.h>
using namespace std;
#define eps 1e-9
#define N 1610
bitset<N> a[N];
int n;
void Gause()
{
  for (int i=0;i<n;i++)
  {
    int now=i;
    for (int j=i;j<n;j++)
      if (a[j][i]>a[now][i]) now=j;
    if (a[now][i])
    {
      swap(a[i],a[now]);
      for (int j=0;j<n;j++)
        if (j!=i&&a[j][i]) a[j]^=a[i];
    } else
    {
      for (int j=0;j<n;j++)
        if (a[j][i]) a[j][i]=0,a[j][n]=a[j][n]^1;
    }
  }
}
#define js(x,y) (x-1)*m1+y-1
#define pd(x,y) if (x>=1&&x<=n1&&y>=1&&y<=m1)
int dx[5]={0,1,0,-1,0};
int dy[5]={0,0,1,0,-1};
int main()
{
  freopen("noi.in","r",stdin);
  freopen("noi.out","w",stdout);
  std::ios::sync_with_stdio(false);
  int n1,m1;
  cin>>n1>>m1;
  n=n1*m1;
  for (int i=1;i<=n1;i++)
    for (int j=1;j<=m1;j++)
      for (int k=0;k<=4;k++)
        pd(i+dx[k],j+dy[k])
        {
          a[js(i,j)][js(i+dx[k],j+dy[k])]=1;
        }
  Gause();
  for (int i=1;i<=n1;i++)
  {
    for (int j=1;j<=m1;j++)
    {
      int x=js(i,j);
      if (!a[x][x]|a[x][n]) cout<<1<<" ";
      else cout<<0<<" ";
    }
    cout<<endl;
  }
  return 0;
}