迷宫问题

①用递归做，会超时

#include <iostream>
#include <string>
#include <stack>
#include <queue>
using namespace std;

int maze[1005][1005];
int mark[1005][1005];
int xb,yb,xe,ye;

struct position
{
    int px,py;
}point[9999];

struct Offsets
{
    int dx,dy;
    Offsets(int x=0,int y=0):dx(x),dy(y) {}
};
Offsets guide[4]= { {1,0},{0,-1},{-1,0},{0,1} };
int f=0;
void dfs(int xb,int yb,int step)
{

    if(xb==xe && yb==ye)
    {
       for(int i=0;i<step;i++)
        cout<<point[i].py<<" "<<point[i].px<<endl;
     //   cout<<endl;
        f=1;
       return;
    }
    for(int i=0;i<4;i++)
    {
        int x = xb+guide[i].dx;
        int y = yb+guide[i].dy;
        if(mark[x][y] == 0 || mark[x][y]==4)
        {
            mark[x][y] = 1;
            point[step].px = x;
            point[step].py = y;
            dfs(x,y,step+1);
            if(f==1)
        return;
            mark[x][y] = 0;
        }
    }
    if(f==1)
        return;
}


int main()
{
    int N,M;
    cin>>N>>M;
    //初始化
    for(int i=0; i<M; i++)
        for(int j=0; j<N; j++)
        {
            cin>>maze[i][j];
            mark[i][j] = maze[i][j];
            if(maze[i][j] == 3)
            {
                xb = i;
                yb = j;
            }
            if(maze[i][j] == 4)
            {
                xe = i;
                ye = j;
            }
        }
    /*  for(int i=0; i<M; i++)
      {
          for(int j=0; j<N; j++)
              cout<<maze[i][j];
          cout<<endl;
      }*/
    point[0].px = xb;
    point[0].py = yb;
    dfs(xb,yb,1);
    return 0;
}
/*
8 10
1 1 1 1 1 1 1 1
1 0 1 1 0 1 0 1
1 0 1 0 0 1 0 1
1 1 0 3 1 0 1 1
1 0 0 1 0 0 4 1
1 0 0 0 0 1 1 1
1 0 1 0 0 1 0 1
1 0 1 0 0 0 1 1
1 1 1 1 0 0 0 1
1 1 1 1 1 1 1 1
*/

 ②用栈的思想做

#include <iostream>
#include <string>
#include <stack>
#include <queue>
using namespace std;
/*
8 10
1 1 1 1 1 1 1 1
1 0 1 1 0 1 0 1
1 0 1 0 0 1 0 1
1 1 0 3 1 0 1 1
1 0 0 1 0 0 4 1
1 0 0 0 0 1 1 1
1 0 1 0 0 1 0 1
1 0 1 0 0 0 1 1
1 1 1 1 0 0 0 1
1 1 1 1 1 1 1 1
*/
int maze[1005][1005];
int mark[1005][1005];
int xb,yb,xe,ye;

struct position
{
    int px,py;
} point[99999];

struct Offsets
{
    int dx,dy;
    Offsets(int x=0,int y=0):dx(x),dy(y) {}
};
Offsets guide[4]= { {1,0},{0,-1},{-1,0},{0,1} };

int main()
{
    int N,M;
    cin>>N>>M;
    //初始化
    for(int i=0; i<M; i++)
        for(int j=0; j<N; j++)
        {
            cin>>maze[i][j];
            mark[i][j] = maze[i][j];
            if(maze[i][j] == 3)
            {
                xb = i;
                yb = j;
            }
            if(maze[i][j] == 4)
            {
                xe = i;
                ye = j;
            }
        }
    /*  for(int i=0; i<M; i++)
      {
          for(int j=0; j<N; j++)
              cout<<maze[i][j];
          cout<<endl;
      }*/
    point[0].px = xb;
    point[0].py = yb;
    int t = 0;
    while(1)
    {
       int ff = 0;
        for(int i=0; i<4; i++)
        {
            int x = point[t].px+guide[i].dx;
            int y = point[t].py+guide[i].dy;
            if(mark[x][y] == 0 && maze[x][y] == 0)
            {
               t++;
                mark[x][y] = 1;
                point[t].px = x;
                point[t].py = y;
                ff = 1;
                break;
            }
            if(maze[x][y] == 4)
            {
                for(int i = 0; i <= t; i++)
                    cout<<point[i].py<<' '<<point[i].px<<endl;
                cout<<y<<' '<<x<<endl;
               return 0;
            }
        }
        if(ff==0)
            t--;
    }
    return 0;
}