迷宫的最短路径

#include<bits/stdc++.h>
#define maxn 100004
#define inf 0x3f3f3f3f
using namespace std;
typedef pair<int,int> p;
int sx,sy;
int gs,gy;
char a[maxn][maxn];
int  dis[maxn][maxn];
int dx={1,0,-1,0};
int dy={0,1,0,-1};


int bfs(){
	queue<p> que;
		for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
	    dis[i][j] = inf;
		}
	}
		que.push(p(sx,sy));
		d[sx][sy] = 0;
		
		while(que.size()){
			p  = que.front();que.pop();
			if(p.first == gx && p.second == gy) break;
			
			for(int i=0;i<4;i++){
				int nx = p.first + dx[i],ny = p.second + dy[i];
				
				if(nx>=1 && nx<=n && ny>=1 && ny<=m && a[nx][ny]!='#' && dis[nx][ny]==inf){
					que.push(p(nx,ny));
					dis[nx][ny] = dis[p.first][p.second] + 1; 
				}
 			}
		}
		return dis[gx][gy];
	
}
void solve(){
	int res = bfs();
	cout<<res<<endl;
}


int main(){
	int n,m;
	cin>>n>>m;
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			cin>>a[i][j];
			if(a[i][j] == 'S'){
				sx = i;
				sy = j;
			}
			if(a[i][j] == 'G'){
				gs = i;
				gy = j;
			}
		}
	}
	
	solve();
	return 0;
}