【HDU1198】Farm Irrigation（回溯+记忆化搜索）

数据流小，深搜即可。有些暴力。看其他人的题解用二维转换成一维做的并查集很巧妙，马上去研究一下！！

 #include <iostream>
 #include <cstring>
 #include <cstdlib>
 #include <cstdio>
 #include <cmath>
 #include <cctype>
 #include <algorithm>
 #include <numeric>
 #include <string>
 #include <limits.h>
 #include <map>
 using namespace std;

 int m, n, ans = ;
 char Map[][];
 bool vis[][];
 map<char, string> check;

 void dfs (int x, int y) {

     vis[x][y] = ;

     if (check[Map[x][y]].find("U") != - && check[Map[x - ][y]].find("D") != -) {
         if (!vis[x - ][y]) dfs (x - , y);
     }

     if (check[Map[x][y]].find("D") != - && check[Map[x + ][y]].find("U") != -) {
         if (!vis[x + ][y]) dfs (x + , y);
     }

     if (check[Map[x][y]].find("L") != - && check[Map[x][y - ]].find("R") != -) {
         if (!vis[x][y - ]) dfs (x, y - );
     }

     if (check[Map[x][y]].find("R") != - && check[Map[x][y + ]].find("L") != -) {
         if (!vis[x][y + ]) dfs (x, y + );
     }
 }

 int main () {

     check['A'] = "UL";  check['B'] = "UR";  check['C'] = "DL";
     check['D'] = "DR";  check['E'] = "UD";  check['F'] = "LR";
     check['G'] = "ULR"; check['H'] = "UDL"; check['I'] = "DLR";
     check['J'] = "UDR"; check['K'] = "UDLR";

     while (~scanf("%d%d", &m, &n)) {
         if (m <  && n < ) {
             break;
         }
         memset (vis, , sizeof(vis));
         memset (Map, , sizeof(Map));
         for (int i = ; i < m ; ++ i) {
             for (int j =  ; j < n; ++ j) {
                 cin >> Map[i][j];
             }
         }
         ans = ;
         for (int i = ; i < m; ++ i) {
             for (int j = ; j < n; ++j) {
                 if (vis[i][j] != ) {
                     dfs (i, j);
                     ans ++;
                 }
             }
         }

         cout << ans << endl;
     }
     return ;
 }