poj 2375

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
#include <cmath>
#define N 510
using namespace std;
struct Node
{
    int v,next;
}e[N*N*4];
int head[N*N],e_num,num,od[N*N],id[N*N];
int map[N][N],temp_map[N][N];
int dir[][2]={0,1,1,0};
bool vis[N*N];
int low[N*N],stack[N*N],s[N*N],scc_num,top,s_n,p[N*N];
void add_edge( int u, int v)
{
    e[e_num].v=v;
    e[e_num].next=head[u];
    head[u]=e_num++;
}

void get_map(int m, int n )
{
    memset(head,-1,sizeof(head));
    e_num=0;
    for( int i=1; i<=m; i++ )
    {
        for( int j=1; j<=n; j++ )
        {
            for( int k=0; k<2; k++ )
            {
                int x=i+dir[k][0];
                int y=j+dir[k][1];
                if(x>=1&&x<=m&&y>=1&&y<=n)
                {
                    if(map[x][y]<=map[i][j])
                        add_edge(temp_map[i][j],temp_map[x][y]);
                    if(map[x][y]>=map[i][j])
                        add_edge(temp_map[x][y],temp_map[i][j]);
                }
            }
        }
    }
}

void dfs( int u, int dfs_num, int &scc_num)
{
    low[u]=++dfs_num;
    s[++s_n]=u;
    stack[++top]=u;
    for( int i=head[u]; i!=-1; i=e[i].next )
    {
        if(!low[e[i].v])
            dfs(e[i].v,dfs_num,scc_num);
            else if(p[e[i].v]==0)
            {
                while(low[stack[top]]>low[e[i].v])--top;
            }
    }
    if( stack[top]==u )
    {
        top--;
        scc_num++;
        do
        {
            p[s[s_n]]=scc_num;
        }while(s[s_n--]!=u);
    }
    return ;
}
void work()
{
    int scc_num=0,dfs_num=0;
    memset(p,0,sizeof(p));
    memset(low,0,sizeof(low));
    s_n=top=0;
    for( int i=1; i<=num; i++ )
    {
        if(!low[i])dfs(i,dfs_num,scc_num);
    }
    memset(od,0,sizeof(od));
    memset(id,0,sizeof(id));
    for( int u=1;u<=num; u++ )
    {
        for( int i=head[u];i!=-1;i=e[i].next)
        {
            int v=e[i].v;
            if(p[u]!=p[v])od[p[u]]++,id[p[v]]++;
        }
    }
    int i_num=0,o_num=0;
    for( int i=1; i<=scc_num; i++)
    {
        if(!od[i])o_num++;
        if(!id[i])i_num++;
    }
    if(scc_num==1)printf("0\n");
    else printf("%d\n",max(i_num,o_num));
}
int main()
{
   // freopen("in.txt","r",stdin);
    int W,L;
    while( ~scanf("%d%d",&W,&L))
    {
        num=0;
        for( int i=1;i<=L; i++ )
        for( int j=1;j<=W; j++ )
        {
            scanf("%d",&map[i][j]);
            temp_map[i][j]=++num;
        }
        get_map(L,W);
        work();
    }
    return 0;
}