【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！！
1 #include <iostream> 2 #include <cstring> 3 #include <cstdlib> 4 #include <cstdio> 5 #include <cmath> 6 #include <cctype> 7 #include <algorithm> 8 #include <numeric> 9 #include <string> 10 #include <limits.h> 11 #include <map> 12 using namespace std; 13 14 int m, n, ans = 0; 15 char Map[55][55]; 16 bool vis[55][55]; 17 map<char, string> check; 18 19 void dfs (int x, int y) { 20 21 vis[x][y] = 1; 22 23 if (check[Map[x][y]].find("U") != -1 && check[Map[x - 1][y]].find("D") != -1) { 24 if (!vis[x - 1][y]) dfs (x - 1, y); 25 } 26 27 if (check[Map[x][y]].find("D") != -1 && check[Map[x + 1][y]].find("U") != -1) { 28 if (!vis[x + 1][y]) dfs (x + 1, y); 29 } 30 31 if (check[Map[x][y]].find("L") != -1 && check[Map[x][y - 1]].find("R") != -1) { 32 if (!vis[x][y - 1]) dfs (x, y - 1); 33 } 34 35 if (check[Map[x][y]].find("R") != -1 && check[Map[x][y + 1]].find("L") != -1) { 36 if (!vis[x][y + 1]) dfs (x, y + 1); 37 } 38 } 39 40 int main () { 41 42 check['A'] = "UL"; check['B'] = "UR"; check['C'] = "DL"; 43 check['D'] = "DR"; check['E'] = "UD"; check['F'] = "LR"; 44 check['G'] = "ULR"; check['H'] = "UDL"; check['I'] = "DLR"; 45 check['J'] = "UDR"; check['K'] = "UDLR"; 46 47 while (~scanf("%d%d", &m, &n)) { 48 if (m < 0 && n < 0) { 49 break; 50 } 51 memset (vis, 0, sizeof(vis)); 52 memset (Map, 0, sizeof(Map)); 53 for (int i = 0; i < m ; ++ i) { 54 for (int j = 0 ; j < n; ++ j) { 55 cin >> Map[i][j]; 56 } 57 } 58 ans = 0; 59 for (int i = 0; i < m; ++ i) { 60 for (int j = 0; j < n; ++j) { 61 if (vis[i][j] != 1) { 62 dfs (i, j); 63 ans ++; 64 } 65 } 66 } 67 68 cout << ans << endl; 69 } 70 return 0; 71 }
