题解

这题也能用广搜，具体我就不多讲了。
代码如下：

#include<bits/stdc++.h>
using namespace std;

char a[3005][3005];
int dx[4] = {1,-1,0,0},dy[4] = {0,0,1,-1};
bool vis[3005][3005];

struct node{
	int x,y,step;
};

int main(){
	int n,m;
    cin >> n >> m;
    for(int i = 0;i < n;i ++){
    	for(int j = 0;j < m;j ++){
        	cin >> a[i][j];
        }
    }
    queue<node> q;
    q.push({0,0,0});
    while(!q.empty()){
    	int ix = q.front().x,iy = q.front().y,istep = q.front().step;
        q.pop();
        if(ix == n - 1 and iy == m - 1){
        	cout << istep;
            return 0;
        }
        for(int i = 0;i < 4;i ++){
            int nx = ix,ny = iy;
        	while(a[nx + dx[i]][ny + dy[i]] == '*' and nx + dx[i] >= 0 and ny + dy[i] >= 0 and nx + dx[i] < n and ny + dy[i] < m){
            	nx += dx[i];
                ny += dy[i];
            }
            if((nx != ix or ny != iy) and vis[nx][ny] == 0){
                vis[nx][ny] = 1;
                q.push({nx,ny,istep + 1});
            }
            nx = ix + dx[i],ny = iy + dy[i];
            if(a[nx][ny] != '#' and nx >= 0 and ny >= 0 and nx < n and ny < m and vis[nx][ny] == 0){
            	vis[nx][ny] = 1;
                q.push({nx,ny,istep + 1});
            }
        }
    }
    cout << -1;
	return 0;
}