Codeforces Round #220 (Div. 2) Question C: Inna and Dima (Memory Search DP)_html/css_WEB-ITnose

Question address: http://codeforces.com/problemset/problem/374/C

Use dp[i][j] to represent the number in row i and column j. You can go maximum distance. When it is -1, it means that it has not been walked, and the ones that have been walked but not finished are temporarily marked as INF. In this way, if there is a cycle, INF will be returned. Then search with dfs.

The code is as follows:

#include <iostream>#include <cstdio>#include <string>#include <cstring>#include <stdlib.h>#include <math.h>#include <ctype.h>#include <queue>#include <map>#include <set>#include <algorithm>using namespace std;#define LL __int64const int INF=0x3f3f3f3f;char mp[1001][1001], str[]="DIMA";int dp[1001][1001];int jx[]={0,0,1,-1};int jy[]={1,-1,0,0};int n, m;int dfs(int x, int y, int tmp){    if(dp[x][y]!=-1) return dp[x][y];    dp[x][y]=INF;    int i, a, b, t=0;    tmp=(1+tmp)%4;    for(i=0;i<4;i++)    {        a=x+jx[i];        b=y+jy[i];        if(a>=0&&a<n&&b>=0&&b<m&&mp[a][b]==str[tmp])        {            t=max(t,dfs(a,b,tmp));        }    }    dp[x][y]=++t;    return t;}int main(){    int i, j, max1=0;    scanf("%d%d",&n,&m);    for(i=0;i<n;i++)    {        scanf("%s",mp[i]);    }    memset(dp,-1,sizeof(dp));    for(i=0;i<n;i++)    {        for(j=0;j<m;j++)        {            if(mp[i][j]=='D')            {                max1=max(max1,dfs(i,j,0));            }        }    }    if(max1/4==0)    {        puts("Poor Dima!");    }    else if(max1>=INF)    {        puts("Poor Inna!");    }    else        printf("%d\n",max1/4);    return 0;}