poj 1088 dp **

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记忆化搜索很好写

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cstring>
#include<cmath>
#include<queue>
#include<map>
using namespace std;
#define MOD 1000000007
const int INF=0x3f3f3f3f;
const double eps=1e-5;
typedef long long ll;
#define cl(a) memset(a,0,sizeof(a))
#define ts printf("*****
");
const int MAXN=1005;
int n,m,tt;
int a[MAXN][MAXN];
int dp[MAXN][MAXN];
int d[4][2]={1,0,0,1,-1,0,0,-1};
int fun(int x,int y)
{
    if(dp[x][y]>0)    return dp[x][y];
    dp[x][y]=1;
    for(int i=0;i<4;i++)
    {
        int nx=x+d[i][0];
        int ny=y+d[i][1];
        if(nx>=1&&nx<=n&&ny>=1&&ny<=m&&a[x][y]>a[nx][ny])
        {
            if(dp[x][y]<fun(nx,ny)+1)
                dp[x][y]=dp[nx][ny]+1;
        }
    }
    return dp[x][y];
}
int main()
{
    int i,j,k;
    #ifndef ONLINE_JUDGE
    freopen("1.in","r",stdin);
    #endif
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        for(i=1;i<=n;i++)
        {
            for(j=1;j<=m;j++)
            {
                scanf("%d",&a[i][j]);
            }
        }
        memset(dp,-1,sizeof(dp));
        int ans=0;
        for(i=1;i<=n;i++)
            for(j=1;j<=m;j++)
            {
                if(fun(i,j)>ans) ans=dp[i][j];
            }
        printf("%d
",ans);
    }
}