只过了前两个测试点,只有28分,为什么? c++代码

#include <iostream>
#include <algorithm>
#include <cmath>
using namespace std;
const int N = 1e3 + 100;
int Book[N][N];

void dfs(int k, int x, int y, int lx, int ly) // x,y是上一次画的图像坐标, lx, ly是偏移量
{
    if (k <= 0) return ;
    int len = pow(2, k);
    int tx, ty; tx = ty = len / 2;
    tx += lx; ty += ly;
    int t;
    if (x > tx & y > ty)
    {
        t = 4;
        if (Book[tx][ty] || Book[tx + 1][ty] || Book[tx][ty + 1])
        {
            if (Book[tx][ty]) tx++, ty++, t = 1;
            else if (Book[tx + 1][ty]) ty++, t = 3;
            else if (Book[tx][ty + 1]) tx++, t = 2;
        }
        cout<<tx<<" "<<ty<<" "<<t<<endl;
    }
    else if (x > tx && y <= ty)
    {
        t = 3;
        ty++;
        if (Book[tx][ty] || Book[tx][ty - 1] || Book[tx + 1][ty])
        {
            if (Book[tx][ty]) tx++, ty--, t = 2;
            else if (Book[tx][ty - 1]) tx++, t = 1;
            else if (Book[tx + 1][ty]) ty--, t = 4;
        }
        cout<<tx<<" "<<ty<<" "<<t<<endl;
    }
    else if (x <= tx && y > ty)
    {
        t = 2;
        tx++;
        if (Book[tx][ty] || Book[tx - 1][ty] || Book[tx][ty + 1])
        {
            if (Book[tx][ty]) tx--, ty++, t = 3;
            else if (Book[tx - 1][ty]) ty++, t = 1;
            else if (Book[tx][ty + 1]) tx--, t = 4;
        }
        cout<<tx<<" "<<ty<<" "<<t<<endl;
    }
    else if (x <= tx && y <= ty)
    {
        t = 1;
        tx++, ty++;
        if (Book[tx][ty] || Book[tx][ty - 1] || Book[tx - 1][ty])
        {
            if (Book[tx][ty]) tx--, ty--, t = 4;
            else if (Book[tx][ty - 1]) tx--, t = 3;
            else if (Book[tx - 1][ty]) ty--, t = 2;
        }
        cout<<tx<<" "<<ty<<" "<<t<<endl;
    }
    Book[tx][ty] = 1;
    if (t == 1) Book[tx][ty - 1] = Book[tx - 1][ty] = 1;
    else if (t == 2) Book[tx][ty + 1] = Book[tx - 1][ty] = 1;
    else if (t == 3) Book[tx][ty - 1] = Book[tx + 1][ty] = 1;
    else if (t == 4) Book[tx][ty + 1] = Book[tx + 1][ty] = 1;
    dfs(k - 1, tx, ty, lx, ly);
    dfs(k - 1, tx, ty, lx, ly + len / 2);
    dfs(k - 1, tx, ty, lx + len / 2, ly);
    dfs(k - 1, tx, ty, lx + len / 2, ly + len / 2);
}

int main()
{
    int x, y, k;
    cin>>k>>x>>y;
    Book[x][y] = 1;
    dfs(k, x, y, 0, 0);
    return 0;
}