RT，一般思路，WA#3#5#6#8，代码如下

/*
By Nero Claudius Caeser Augustus Germanicus,
Imeratorum Romanorum.
*/
#include <bits/stdc++.h>

using namespace std;

namespace StandardIO{

	template<typename T>void read(T &x){
		x=0;T f=1;char c=getchar();
		for(; c<'0'||c>'9'; c=getchar()) if(c=='-') f=-1;
		for(; c>='0'&&c<='9'; c=getchar()) x=x*10+c-'0';
		x*=f;
	}

	template<typename T>void write(T x){
		if(x<0) putchar('-'),x*=-1;
		if(x>=10) write(x/10);
		putchar(x%10+'0');
	}

} using namespace StandardIO;

namespace Project{
	
	const int N=2000+10;
	const int dis[8][2]={{3,1},{3,-1},{1,3},{1,-3},{-3,1},{-3,-1},{-1,3},{-1,-3}};
	
	int n,m,K,ans,S,T;
	int cnt=1;
	int head[N*N];
	struct node{
		int to,next,val;
	} edge[N*N];
	int dep[N*N];
	queue<int> q;
	int block[N][N];
	
	inline void _add(int a,int b,int c){
		edge[++cnt].to=b,edge[cnt].val=c,edge[cnt].next=head[a],head[a]=cnt;
	}
	inline void add(int a,int b,int c){
		_add(a,b,c),_add(b,a,0);
	}
	bool bfs(){
		memset(dep,0,sizeof(dep));
		dep[S]=1,q.push(S);
		while(q.size()){
			int now=q.front();q.pop();
			for(int i=head[now]; i; i=edge[i].next){
				int to=edge[i].to;
				if(edge[i].val&&!dep[to]){
					dep[to]=dep[now]+1;
					q.push(to);
				}
			}
		}
		return dep[T];
	}
	int dfs(int now,int f){
		if(now==T) return f;
		int used=0;
		for(int i=head[now],w; i; i=edge[i].next){
			int to=edge[i].to;
			if(edge[i].val&&dep[to]==dep[now]+1){
				w=dfs(to,min(f-used,edge[i].val));
				edge[i].val-=w,edge[i^1].val+=w,used+=w;
				if(used==f) return f;
			}
		}
		if(!used) dep[now]=-1;
		return used;
	}
	void dinic(){
		while(bfs()) ans+=dfs(S,2147400000);
	}
	
	void MAIN(){
		read(n),read(m),read(K),S=0,T=n*m+1;
		for(int i=1,x,y; i<=K; ++i){
			read(x),read(y);
			block[x][y]=1;
		}
		for(int i=1; i<=n; ++i){
			for(int j=1,cur; j<=m; ++j){
				cur=j+(i-1)*m;
				if(i&1){
					add(S,cur,1);
				}else{
					add(cur,T,1);
				}
			}
		}
		for(int i=1; i<=n; ++i){
			for(int j=1,cur; j<=m; ++j){
				if(block[i][j]) continue;
				if(i&1){
					cur=j+(i-1)*m;
					for(int k=0,x,y; k<8; ++k){
						x=i+dis[k][0],y=j+dis[k][1];
						if(x<1||x>n||y<1||y>m||block[x][y]) continue;
						add(cur,y+(x-1)*m,1);
					}	
				}
			}
		}
		dinic();
		write(n*m-K-ans);
	}
	
}

int main(){
//	freopen(".in","r",stdin);
//	freopen(".out","w",stdout);
	Project::MAIN();
}

谢谢！