POJ 1088 DP || 记忆化搜索

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按高度从小到大排序一遍 DP即可:

#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;}

裸记忆化搜索：

<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;}

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