经典迷宫问题—BFS

参考：刘汝佳《算法竞赛入门经典》第六章：数据结构基础

源代码：

#include <stdio.h> #define MAXN 10 int dx[] = {-1, 1, 0, 0}, dy[] = {0, 0, -1, 1}; char name[] = {'U', 'D', 'L', 'R'}; int q[MAXN * MAXN]; //队列，保存当前结点编号 int vis[MAXN][MAXN], nMap[MAXN][MAXN]; int m, n; //行、列数 int dir[MAXN * MAXN]; int fa[MAXN][MAXN], dis[MAXN][MAXN], last_dir[MAXN][MAXN]; void funcInit(); void bfs(int x, int y); void funcInput(); void print_path(int x, int y); int main() { funcInput(); funcInit(); bfs(0, 0); print_path(m - 1, n - 1); return 0; } void funcInit() { int i, j; for (i = 0; i != m; ++i) { for (j = 0; j != n; ++j) { vis[i][j] = 0; dis[i][j] = 0; } } } void funcInput() { int i, j; scanf("%d %d", &m, &n); for (i = 0; i != m; ++i) { for (j = 0; j != n; ++j) { scanf("%d", &nMap[i][j]); } } } void bfs(int x, int y) { int front = 0, rear = 0; int d, u; //方向标记、结点编号 u = x * m + y; vis[x][y] = 1; fa[x][y] = u; q[rear++] = u; //将当前结点编好放入队列 while (front != rear) { u = q[front++]; x = u / m; y = u % m; for (d = 0; d != 4; ++d) { int nx = x + dx[d], ny = y + dy[d]; if (nx >= 0 && nx < m && ny >= 0 && ny < n && !vis[nx][ny] && !nMap[nx][ny]) { int v = nx * m + ny; q[rear++] = v; vis[nx][ny] = 1; fa[nx][ny] = u; dis[nx][ny] = dis[x][y] + 1; //记录路径长度 last_dir[nx][ny] = d; //记录移动方向标记 } } } } void print_path(int x, int y) { int c = 0; while (1) { int fx = fa[x][y] / m; int fy = fa[x][y] % m; if (fx == x && fy == y) break; dir[c++] = last_dir[x][y]; x = fx; y = fy; } while (c--) { putchar(name[dir[c]]); putchar('/n'); } printf("最短路径长度为:%d/n", dis[m-1][n-1]); }