自闭了

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;

const int MAXN=1000005,MAXM=2000005,INF=10211314;
struct node{
    int u,v,c;
    node*next,*rev;
}*h[MAXN],pool[MAXM];
int a[205][205],lv[MAXN],q[MAXN],n,m,src,sink,tot=0,inf=291433;
int pos[8][2]={1,2, 2,1, 1,-2, 2,-1, -1,2, -2,1, -1,-2, -2,-1};

void addedge(int u,int v,int c){
//  cout<<u<<" "<<v<<" "<<c<<endl;
    node*p=&pool[++tot];
    node*r=&pool[++tot];
    p->u=u;p->v=v;p->c=c;p->next=h[u];h[u]=p;p->rev=r;
    r->u=v;r->v=u;r->c=c;r->next=h[v];h[v]=r;r->rev=p;
}

bool bfs(){
    memset(lv,-1,sizeof(lv));
    int front=0,rear=0;
    q[rear++]=src;
    lv[src]=0;
    while(front<rear){
        int u=q[front++];
        for(node*p=h[u];p;p=p->next){
            if(lv[p->v]<0&&p->c>0){
                lv[p->v]=lv[u]+1;
                q[rear++]=p->v;
            }
        }
        if(lv[sink]>0){
            return 1;
        }
    }
    return lv[sink]>0;
}

int dfs(int u,int key){
    if(u==sink){
        return key;
    }
    int res=0;
    for(node*p=h[u];p;p=p->next){
        if(lv[p->v]==lv[u]+1&&p->c>0){
            int tmp=dfs(p->v,min(p->c,key));
            if(tmp){
                p->c-=tmp;
                p->rev->c+=tmp;
                res+=tmp;
                key-=tmp;
                if(key<=0){
                    break;
                }
            }
        }
    }
    if(res==0){
        lv[u]=-1;
    }
    return res;
}

int dinic(){
    int totflow=0;
    while(bfs())
        totflow+=dfs(src,INF);
    return totflow;
}

int main(){
    scanf("%d%d",&n,&m);
    src=n*n+1;sink=src+1;
    for(int i=1;i<=m;i++){
        int x,y;
        scanf("%d%d",&x,&y);
        a[x][y]=1;
    }
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            if(a[i][j]==1){
                continue;
            }
            if((i+j)%2==1){
                addedge(src,n*(i-1)+j,1);
                for(int k=0;k<8;k++){
                    int x=pos[k][0]+i,y=pos[k][1]+j;
                    if(x>=1&&x<=n&&y>=1&&y<=n){
                        addedge(n*(i-1)+j,n*(x-1)+y,inf);
                    }
                }
            }
            else{
                addedge(n*(i-1)+j,sink,1);
            }
        }
    }
    printf("%d\n",n*n-m-dinic());
    return 0;
}

AC*4

WA*8