POJ 1088 DP || 记忆化搜索

#include "stdio.h"
#include "string.h"
#include "queue"
#include "algorithm"
using namespace std;

int dir[4][2]={1,0,-1,0,0,1,0,-1};
int n,m,Min,ans;
int a[101][101],dp[101][101];

struct node
{
int x,y,h;
}data[10010];

bool cmp(const node a,const node b)
{
return a.h<b.h;
}
void bfs()
{
int sum,i,j,x,y;
sum=0;
for (i=1;i<=n;i++)
for (j=1;j<=m;j++)
{
data[sum].x=i;
data[sum].y=j;
data[sum].h=a[i][j];
sum++;
}
sort(data,data+sum,cmp);

for (i=0;i<sum;i++)
{
for (j=0;j<4;j++)
{
x=data[i].x+dir[j][0];
y=data[i].y+dir[j][1];
if (x<1 || x>n || y<1 || y>m) continue;
if (a[x][y]<=a[data[i].x][data[i].y]) continue;
dp[x][y]=max(dp[x][y],dp[data[i].x][data[i].y]+1);
}
}
}

int main()
{
int i,j;
while (scanf("%d%d",&n,&m)!=EOF)
{

Min=10010;
for (i=1;i<=n;i++)
for (j=1;j<=m;j++)
{
scanf("%d",&a[i][j]);
dp[i][j]=1;
}

bfs();
ans=1;
for (i=1;i<=n;i++)
for (j=1;j<=m;j++)
if (dp[i][j]>ans) ans=dp[i][j];

printf("%d\n",ans);
}
return 0;
}

<pre name="code" class="cpp">#include "stdio.h"
#include "string.h"
int dir[4][2]={1,0,-1,0,0,1,0,-1};
int n,m;
int dp[101][101];
int a[101][101];
int M(int a,int b)
{
if (a<b) return b;
else return a;
}
int  bfs(int x,int y)
{
int ans,i;
if (x<1 || x>n || y<1 || y>m) return -1;
if (dp[x][y]!=-1) return dp[x][y];

ans=1;
for (i=0;i<4;i++)
{
if (x+dir[i][0]<1 || x+dir[i][0]>n || y+dir[i][1]<1 || y+dir[i][1]>m) continue;
if (a[x][y]<=a[x+dir[i][0]][y+dir[i][1]]) continue;
ans=M(ans,bfs(x+dir[i][0],y+dir[i][1])+1);
}
dp[x][y]=ans;
return ans;
}
int main()
{
int Max,i,ans,j;
while (scanf("%d%d",&n,&m)!=EOF)
{

Max=0;
for (i=1;i<=n;i++)
for (j=1;j<=m;j++)
{
scanf("%d",&a[i][j]);
if (a[i][j]>Max) Max=a[i][j];
}

memset(dp,-1,sizeof(dp));
ans=1;
for (i=1;i<=n;i++)
for (j=1;j<=m;j++)
{
ans=M(bfs(i,j),ans);
}
printf("%d\n",ans);

}
return 0;
}