题目

5
4 2 1 4
01010
11100
11111
10011
10001
out
no

思路

回溯法
设置maze数组保存数据
设置mark数组记录是否走过该路径
设置route栈记录走过的地方（回溯
设置mv数组来表示步数
当栈不为空的时候走遍栈顶的每一条路线，直到遇见mark是0且maze是0的路线，否则返回上一级，直到栈空or找到路为止

代码

#include<iostream>
using namespace std;
struct STACK{int x,y,d;};
struct MOVE{int a,b;};
char maze[100][100];
int mark[100][100];
STACK route[100*100];
MOVE mv[8];
int top;
int n;

int getmazepath(int x1, int y1, int x2, int y2)
{
    int now_x,now_y,dir,next_x,next_y,t;
    if(maze[x1][y1] != '0' || maze[x2][y2] != '0')
        return 1;

    route[0].x = x1;
    route[0].y = y1;
    route[0].d = -1;
    top = 1;
    mark[x1][y1] = 1;
    while(top > 0)
    {
        now_x = route[--top].x;
        now_y = route[top].y;
        dir = route[top].d;
        while(dir < 7)
        {
            next_x = now_x + mv[++dir].a;
            next_y = now_y + mv[dir].b;
            if(next_x < 0 || next_y < 0 || next_x >= n || next_y >= n )
                continue;
            if(next_x == x2 && next_y == y2)
            {
                // for(t = 0; t < top; t++)
                //     printf("%3d%3d%3d;",route[t].x,route[t].y,route[t].d);
                // printf("%3d%3d%3d;",i,j,k);
                // printf("%3d%3d%3d;\n",x2,y2,-1);
                return 0;
            }
            if(maze[next_x][next_y] == '0' && mark[next_x][next_y] == 0)
            {
                mark[next_x][next_y] = 1;
                route[top].x = now_x;
                route[top].y = now_y;
                route[top++].d = dir;
                now_x = next_x;
                now_y = next_y;
                dir = -1;
            }
        }
    }
    
    return 1;
}

int main()
{
    cin >> n;
    int x1,y1,x2,y2;
    cin >> x1 >> y1 >> x2 >> y2;
    for(int i = 0; i < n; i++)
        for(int j = 0; j < n ; j++)
        {
            mark[i][j] = 0;
            cin >> maze[i][j];
        }
    // for(int i = 0; i < n; i++)
    // {
    //     for(int j = 0; j < n; j++)
    //         cout << maze[i][j];
    //     cout << endl;
    // }

    mv[0].a = -1; mv[0].b = 0;
    mv[1].a = -1; mv[1].b = 1;
    mv[2].a = 0; mv[2].b = 1;
    mv[3].a = 1; mv[3].b = 1;
    mv[4].a = 1; mv[4].b = 0;
    mv[5].a = 1; mv[5].b = -1;
    mv[6].a = 0; mv[6].b = -1;
    mv[7].a = -1; mv[7].b = -1;
    if(getmazepath(x1,y1,x2,y2))
        cout << "no" << endl;
    else
        cout << "yes" << endl;
    
}