#include <bits/stdc++.h>
using namespace std;

const int N = 1e3 + 5, INF = 2e9, MOD = 1e9 + 7;

inline int read()
{
	char ch = getchar();
	int x = 0;
	while (ch < '0' || ch > '9') ch = getchar();
	while (ch >= '0' && ch <= '9')
	{
		x = (x << 1) + (x << 3) + (ch ^ 48);
		ch = getchar();
	}
	return x;
}

void write(const int x)
{
	if (x > 9) write(x / 10);
	putchar(x % 10 + '0');
}

int n, m, t, k;
bool a[N][N];

struct Node
{
	int x, y, p;
	Node(int _x, int _y, int _p): x(_x), y(_y), p(_p){}
};

struct Node2
{
	int x, y;
}q[N * N];

int dis[N][N];
int sx, sy, ex, ey;

int dx[] = { 0, 0, -1, 1 };
int dy[] = { -1, 1, 0, 0 };

void bfs()
{
	queue<Node> q;
	q.push(Node(ex, ey, 0));
	while (q.size())
	{
		Node l = q.front();
		q.pop();
		if (dis[l.x][l.y] != -1) continue;
		dis[l.x][l.y] = l.p;
		for (register int i = 0; i < 4; ++i)
		{
			int nx = l.x + dx[i], ny = l.y + dy[i];
			if (nx >= 1 && nx <= n && ny >= 1 && ny <= m && !a[nx][ny] && dis[nx][ny] == -1)
			{
				q.push(Node(nx, ny, l.p + 1));
			}
		} 
	}
}

signed main()
{
	// freopen("*.in", "r", stdin);
	// freopen("*.out", "w", stdout);
	t = read();
	while (t--)
	{
		n = read(), m = read();
		for (register int i = 1; i <= n; ++i)
		{
			for (register int j = 1; j <= m; ++j)
			{
				char c;
				scanf(" %c", &c);
				a[i][j] = c - '0';
				dis[i][j] = -1;
			}
		}
		k = read();
		for (register int i = 1; i <= k; ++i) q[i].x = read(), q[i].y = read();
		sx = read(), sy = read(), ex = read(), ey = read();
		bfs();
		int kl = dis[sx][sy];
		if (kl == -1) printf("F\n");
		else
		{
			bool f(1);
			for (register int i(1); i <= k; ++i)
			{
				if (dis[q[i].x][q[i].y] != -1 && dis[q[i].x][q[i].y] <= kl)
				{
					f = false;
					break;
				}
			}
			if (f) printf("T\n");
			else printf("F\n");
		}
	}
	return 0;
}

这份代码复杂度应该是 $O(nmt)$ 的，为什么会被卡超时几十毫秒。

是常数问题还是复杂度问题？