spj TLE了？

我找了考试的数据来测试，程序是没问题的

https://www.luogu.com.cn/record/196629753

我的代码：

#include <cstdio>
#include <cassert>
#include <cstdlib>
#include <cmath>
#include <cstring>

#include <vector>
#include <array>
#include <iostream>
#include <numeric>
#include <random>
#include <algorithm>
#include <string>
#include <map>
#include <set>
#include <stack>
#include <queue>

#define rep(i, n) for (int i = 1, i##num=(n); i <= i##num; i++)
#define rep0(i, n) for (int i = 0, i##num=(n); i < i##num; i++)
#define rep2(i, x, y) for(int i=(x), i##num=(y); i <= i##num; i++)
#define repr(i, x, y) for(int i=(x), i##num=(y); i >= i##num; i--)

using namespace std;

using LL = long long;

const int maxn = 6;
const LL inf = 1000000000000LL;

int n, m;
char a[maxn][maxn];

bool b[maxn][maxn], result[maxn][maxn];

int ans, startx, starty;

bool vis[maxn][maxn];



constexpr int dx[4]={1,-1,0,0};
constexpr int dy[4]={0,0,1,-1};
int cnt_connected;
void dfs2_check(int x, int y){
    cnt_connected++;
    vis[x][y] = true;
    rep0(dir, 4){
        int x2 = x + dx[dir];
        int y2 = y + dy[dir];
        if (0<=x2&&x2<n&&0<=y2&&y2<m)
            if(b[x2][y2] && !vis[x2][y2])
                dfs2_check(x2, y2);
    }
}
bool is_connected(int expected_num){
    memset(vis, false, sizeof(vis));
    cnt_connected = 0;
    dfs2_check(startx, starty);
    return cnt_connected == expected_num;
}

int cnt_later[maxn][maxn];

void dfs(int x, int y, int cur, int cur_edge){
    if (cur > 0 && cur_edge >= cur) return;
    if (cur + cnt_later[x][y] <= ans) return;
    if (x==n){
        if (cur <= ans) return;
        if (cur_edge != cur - 1) return;
        if (is_connected(cur)){
            ans = cur;
            rep0(i, n) rep0(j, m) result[i][j] = b[i][j];
        }
        return;
    }
    int x2 = x+(y+1)/m, y2 = (y+1)%m;
    do{
        if (a[x][y] == '#') break;
        if (x>0&&y>0&&b[x-1][y]&&b[x][y-1]&&b[x-1][y-1]) break;
        b[x][y] = true;
        int edge_diff = (x>0&&b[x-1][y]?1:0) + (y>0&&b[x][y-1]?1:0);
        dfs(x2, y2, cur+1, cur_edge + edge_diff);
        b[x][y] = false;
    }while(false);
    if (a[x][y] != '+')
        dfs(x2, y2, cur, cur_edge);
}

int main(){
    #ifdef FISH_LOCAL
    freopen("tmp.in", "r", stdin);
    #endif
    scanf("%d%d", &n, &m);
    rep0(i, n) scanf("%s", a[i]);
    rep0(i, n)
        rep0(j, m)
            if(a[i][j] == '+'){
                startx=i;
                starty=j;
                break;
            }
    int tmp = 0;
    repr(i,n-1,0)
        repr(j,m-1,0){
            if (a[i][j] != '.')
                tmp++;
            cnt_later[i][j] = tmp;
        }
    ans = 0;
    dfs(0, 0, 0, 0);
    rep0(i, n){
        rep0(j, m)
            if(result[i][j])
                printf("+");
            else if (a[i][j] == '#')
                printf("#");
            else
                printf(".");
        printf("\n");
    }

    return 0;
}