[Hdoj] 3500 fling

Difficult to understand. In short, when a ball Colliders with each other, the ball that actively collides will stop, and the other ball will continue to move in the direction of the collision and continue to collide. However, it is impossible to ejection the ball next to it. However, if a ejection B and BC are adjacent, B can ejection C.

  1 #include <iostream>  2 #include <cstdio>  3 #include <cstring>  4 #include <algorithm>  5 using namespace std;  6   7 #define MAXN 10  8   9 typedef struct { 10     int x, y; 11     char d; 12 } node_t; 13  14 node_t nodes[15]; 15 char map[MAXN][MAXN]; 16 int on; 17 // U < L < R < D. 18 int dir[4][2] = {-1,0,0,-1,0,1,1,0}; 19  20 bool check(int x, int y) { 21     return x<0||x>=7||y<0||y>=8; 22 } 23  24 char getDir(int k) { 25     if (k==0) return ‘U‘; 26     if (k==1) return ‘L‘; 27     if (k==2) return ‘R‘; 28     return ‘D‘; 29 } 30  31 bool dfs(int n) { 32     int i, j, k, x, y; 33     bool flag; 34  35     if (n == 0) 36         return true; 37  38     for (i=0; i<7; ++i) { 39         for (j=0; j<8; ++j) { 40             if (map[i][j] == ‘O‘) { 41                 for (k=0; k<4; ++k) { 42                     x = i + dir[k][0]; 43                     y = j + dir[k][1]; 44                     if (check(x, y) || map[x][y]==‘O‘) 45                         continue; 46                     flag = false; 47                     while (!check(x, y)) { 48                         if (map[x][y] == ‘O‘) { 49                             flag = true; 50                             map[x][y] = ‘X‘; 51                             map[x-dir[k][0]][y-dir[k][1]] = ‘O‘; 52                         } 53                         x += dir[k][0]; 54                         y += dir[k][1]; 55                     } 56                     if (flag) { 57                         map[i][j] = ‘X‘; 58                         nodes[n].x = i; 59                         nodes[n].y = j; 60                         nodes[n].d = getDir(k); 61                         if (dfs(n-1)) 62                             return true; 63                         do { 64                             x -= dir[k][0]; 65                             y -= dir[k][1]; 66                             if (map[x][y] == ‘O‘) { 67                                 map[x][y] = ‘X‘; 68                                 map[x+dir[k][0]][y+dir[k][1]] = ‘O‘; 69                             } 70                         } while (x!=i || y!=j); 71                         map[i][j] = ‘O‘; 72                     } 73                 } 74             } 75         } 76     } 77  78     return false; 79 } 80  81 int main() { 82     int i = 0, j; 83     int t = 0; 84  85 #ifndef ONLINE_JUDGE 86     freopen("data.in", "r", stdin); 87 #endif 88  89     while (scanf("%s", &map[i]) != EOF) { 90         for (i=1; i<7; ++i) 91             scanf("%s", &map[i]); 92         on = 0; 93         for (i=0; i<7; ++i) 94             for (j=0; j<8; ++j) 95                 if (map[i][j] == ‘O‘) 96                     ++on; 97         dfs(on-1); 98  99         if (t != 0)100             printf("\n");101         printf("CASE #%d:\n", ++t);102         for(i=on-1; i>=1; --i)103             printf("%d %d %c\n", nodes[i].x, nodes[i].y, nodes[i].d);104         getchar();105         i = 0;106     }107 108     return 0;109 }

 

[Hdoj] 3500 fling