【bzoj3208】花神的秒题计划Ⅰ

#include<algorithm>
#include<iostream> 
#include<cstring>
#include<cstdlib> 
#include<cstdio>
#include<cmath> 
#include<queue>  
using namespace std;
 
typedef long long LL;
 
#define INF 0x7fffffff
#define N 710
 
int n,m;
int aa,bb,cc,dd;
 
int xx[4]={0,0,1,-1},
    yy[4]={1,-1,0,0};
 
int a[N][N],f[N][N];
 
char ch[2];
 
bool v[N][N];
int read()
{
    int x=0,f=1;char ch=getchar();
    while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
    while(ch>=‘0‘&&ch<=‘9‘){x=x*10+ch-‘0‘;ch=getchar();}
    return x*f;
}
void change(int x,int y,int val)
{
    a[x][y]=val;
}
 
void mark(int aa,int bb,int cc,int dd,bool f)
{
    for (int i=aa;i<=bb;i++)
        for (int j=cc;j<=dd;j++)
            v[i][j]=f;
}
 
int dfs(int x,int y)
{
    if (v[x][y])
        return -INF;
    if (f[x][y]!=-1)
        return f[x][y];
    f[x][y]=1;
    for (int i=0;i<4;i++)
    {
        int tx=x+xx[i],
            ty=y+yy[i];
        if (tx<1 || ty<1 || tx>n || ty>n)
            continue;
        if (a[x][y]>a[tx][ty])
            f[x][y]=max(f[x][y],dfs(tx,ty)+1);
    }
    return f[x][y];
}
 
int main()
{
    scanf("%d",&n);
    for (int i=1;i<=n;i++)
        for (int j=1;j<=n;j++)
            scanf("%d",&a[i][j]);
    scanf("%d",&m);
    while (m--)
    {
        scanf("%s",ch);
        if (ch[0]==‘C‘)
        {
            scanf("%d%d%d",&aa,&bb,&cc);
            change(aa,bb,cc);
        }
        if (ch[0]==‘S‘)
        {
            scanf("%d%d%d%d",&aa,&cc,&bb,&dd);
            mark(aa,bb,cc,dd,1);
        }
        if (ch[0]==‘B‘)
        {
            scanf("%d%d%d%d",&aa,&cc,&bb,&dd);
            mark(aa,bb,cc,dd,0);
        }
        if (ch[0]==‘Q‘)
        {
            int maxn=0;
            memset(f,-1,sizeof(f));
            for (int j=1;j<=n;j++)
                for (int k=1;k<=n;k++)
                    maxn=max(maxn,dfs(j,k));
            printf("%d\n",maxn);
        }
    }
    return 0;
}