蓝桥杯练习系统试题集算法提高ADV-147学霸的迷宫

bfs求最短路，保持字典序只需要调整广搜的时候的方向优先顺序为D,L,R,U即可，然后打印路径用一个string不断的往下传，传到最后输出返回

#include 
#include 
#include 
#include 
#include 
#include 

using namespace std;

struct p {
	int x, y, cou; //cou用来记录走到当前位置走的步数 
	string str; //str用来记录路径 
	p() {}
	p(int x, int y, string str, int cou) : x(x), y(y), str(str), cou(cou) {}
};

char mapp[510][510];
bool vis[510][510];
queue
 Q;

int n, m;
//dir按照D,L,R,U的顺序 
int dir[4][2] = { {1, 0}, {0, -1}, {0, 1}, {-1, 0} };

bool check(int x, int y) {
	if (x <0 || x >= n || y <0 || y >= m || vis[x][y])
		return false;
	return true;
}

void bfs() {
	p tp = p(0, 0, "", 0);
	
	while (!Q.empty()) Q.pop(); //初始化队列 
	Q.push(tp);
	vis[0][0] = true;
	
	while (!Q.empty()) {
		p np = Q.front(); Q.pop();
		for (int i = 0; i <4; i++) {
			int cx = dir[i][0], cy = dir[i][1];
			int nx = np.x + cx, ny = np.y + cy;
			string ts = "";
			if (check(nx, ny)) {
				switch(cx) {
					case 1: ts = "D"; break;
					case -1: ts = "U"; break;
					default: break;
				}
				switch(cy) {
					case 1: ts = "R"; break;
					case -1: ts = "L"; break;
					default: break;
				}
				if (nx == n - 1 && ny == m - 1) {
					cout <					cout <					return ;
				}
				Q.push(p(nx, ny, np.str + ts, np.cou + 1));
				vis[nx][ny] = true;
			}
		}
	}
}

int main()
{
	while (~scanf("%d%d", &n, &m)) {
		memset(vis, false, sizeof(vis));
		for (int i = 0; i 			scanf("%s", mapp[i]);
			for (int j = 0; j 				if (mapp[i][j] == '1') vis[i][j] = true;
			}
		}
		bfs();
	}
	return 0;
}

另外一种记录输出路径的方法：

用一个二维数组记录当前位置前一个点的位置信息，和转向信息，最后用一个栈把结果处理下输出

#include 
#include 
#include 
#include 
#include 
#include 

using namespace std;

struct p {
	int x, y, cou; //cou用来记录走到当前位置走的步数 
	p() {}
	p(int x, int y, int cou) : x(x), y(y), cou(cou) {}
};

//node结构体用来保存当前点的前驱位置信息和转向 
struct node {
	int x, y;
	char d;
	node() {}
	node (int x, int y, char d) : x(x), y(y), d(d) {}
}pre[510][510];

//用于最后输出路径 
stack s;

char mapp[510][510];
bool vis[510][510];
queue
 Q;

int n, m;
//dir按照D,L,R,U的顺序 
int dir[4][2] = { {1, 0}, {0, -1}, {0, 1}, {-1, 0} };

bool check(int x, int y) {
	if (x <0 || x >= n || y <0 || y >= m || vis[x][y])
		return false;
	return true;
}

void bfs() {
	p tp = p(0, 0, 0);
	
	while (!Q.empty()) Q.pop(); //初始化队列
	while (!s.empty()) s.pop();
	Q.push(tp);
	vis[0][0] = true;
	
	while (!Q.empty()) {
		p np = Q.front(); Q.pop();
		for (int i = 0; i <4; i++) {
			int cx = dir[i][0], cy = dir[i][1];
			int nx = np.x + cx, ny = np.y + cy;
			char ts;
			if (check(nx, ny)) {
				switch(cx) {
					case 1: ts = 'D'; break;
					case -1: ts = 'U'; break;
					default: break;
				}
				switch(cy) {
					case 1: ts = 'R'; break;
					case -1: ts = 'L'; break;
					default: break;
				}
				if (nx == n - 1 && ny == m - 1) {
					pre[nx][ny] = node(np.x, np.y, ts);
					
					cout <
					for (int tx, ty; nx != 0 || ny != 0; nx = pre[tx][ty].x, ny = pre[tx][ty].y) {
						tx = nx, ty = ny;
						s.push(pre[nx][ny].d);
					}
					while (!s.empty()) {
						printf("%c", s.top());
						s.pop();
					}
					puts("");
					return ;
				}
				Q.push(p(nx, ny, np.cou + 1));
				pre[nx][ny] = node(np.x, np.y, ts);
				vis[nx][ny] = true;
			}
		}
	}
}

int main()
{
	while (~scanf("%d%d", &n, &m)) {
		memset(vis, false, sizeof(vis));
		for (int i = 0; i 			scanf("%s", mapp[i]);
			for (int j = 0; j 				if (mapp[i][j] == '1') vis[i][j] = true;
			}
		}
		bfs();
	}
	return 0;
}