UVA 705 Slash Maze

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题解：把图放大３倍，这样路就出来了，接着只需要向４个方向遍历即可。　如果遍历时超过边界则说明不能构成回路。

#include <cstdio>#include <cstring>char data[80][80], maze[240][240];int row, column, flag, step, dir[4][2] = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};bool find_cycle(int x, int y) {if (x < 0 || x == 3 * row || y < 0 || y == 3 * column) //如果越界，就说明不能构造回路 则 flag = 0return flag = 0;if (maze[x][y] == 1) //如果已来过，就返回return false;maze[x][y] = 1; //标记已来过step++;for (int i = 0; i < 4; i++) //由该位置向 4 个方向遍历迷宫find_cycle(x + dir[i][0], y + dir[i][1]);return flag;}int main () {int t = 0;while (scanf("%d%d", &column, &row), column) {for (int i = 0; i < row && scanf("%s", data[i]); i++);int max = 0 , count = 0;memset(maze, 0, sizeof(maze));for (int i = 0; i < row; i++) //构造迷宫for (int j = 0; j < column; j++)if (data[i][j] == '\\')maze[i * 3][j * 3] = maze[i * 3 + 1][j * 3 + 1] = maze[i * 3 + 2][j * 3 + 2] = 1;elsemaze[i * 3 + 2][j * 3] = maze[i * 3+ 1][j * 3 + 1] = maze[i * 3][j * 3 + 2] = 1;for (int i = 0; i < 3 * row; i++) //寻找回路for (int j = 0; j < 3 * column; j++) {flag = 1, step = 0;if (find_cycle(i, j))count++, max = (step > max ? step : max);}printf("Maze #%d:\n", ++t);count ? printf("%d Cycles; the longest has length %d.\n\n", count, max/3) : printf("There are no cycles.\n\n"); }return 0;}

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