BFS——走迷宫的最小步数

#include<stdio.h>
#include<string.h>
#include<queue>
using namespace std;
const int maxn = 100;
struct node{
    
    
	int x, y;
	int step;
}S, T, Node;

int n, m;              
char maze[maxn][maxn];   // 迷宫信息 
bool inq[maxn][maxn] = {
    
    false};
int X[4] = {
    
    0, 0, 1, -1};
int Y[4] = {
    
    1, -1, 0, 0}; // 增量数组

bool test(int x, int y)
{
    
    
    if(x >= n || x < 0 || y >= m || y < 0) return false;
    if(maze[x][y] == '*') return false;
    if(inq[x][y] == true) return false;
    return true;
} 

int BFS()
{
    
    
	queue<node> Q;
	Q.push(S);
	while(!Q.empty())
	{
    
    
		node top = Q.front();
		Q.pop();
		if(top.x == T.x && top.y == T.y) return top.step;
		for(int i = 0; i < 4; i++)
		{
    
    
			int newX = top.x + X[i];
			int newY = top.y + Y[i];
			if(test(newX, newY))
			{
    
    
				Node.x = newX;
				Node.y = newY;
				Node.step = top.step + 1;
				Q.push(Node);
				inq[newX][newY] = true;
			}
		}
	}
	return -1;
}

int main()
{
    
    
	scanf("%d%d", &n, &m);
	for(int i = 0; i < n; i++)
	{
    
    
		scanf("%s", maze[i]);
	}
	scanf("%d%d%d%d", &S.x, &S.y, &T.x, &T.y);
	S.step = 0;
	printf("%d", BFS());
	return 0;
}