为什么我的代码里面N开1005会WA两个点，开5005才AC，话说数据范围不是 $n \le 1000$ 吗？

#include <iostream>
#include <cstring>

using namespace std;

const int N = 5005, M = 3 * 5005 + 1005, INF = 0x3f3f3f3f;

int n, m, idx;
int h[N], e[M], w[M], ne[M];
int dist[N], q[N], cnt[N];
bool st[N];

void add(int a, int b, int c)
{
	e[idx] = b;
	w[idx] = c;
	ne[idx] = h[a];
	h[a] = idx ++ ;
	return;
}

bool spfa()
{
	memset(dist, -0x3f, sizeof dist);
	memset(st, 0, sizeof st);
	memset(cnt, 0, sizeof cnt);
	int hh = 0, tt = 1;
	q[0] = 0;
	st[0] = 1;
	dist[0] = 0;
	
	while (hh != tt)
	{
		int t = q[hh ++ ];
		if (hh == N) hh = 0;
		st[t] = 0;
		
		for (int i = h[t]; ~i; i = ne[i])
		{
			int j = e[i];
			if (dist[j] < dist[t] + w[i])
			{
				dist[j] = dist[t] + w[i];
				cnt[j] = cnt[t] + 1;
				if (cnt[j] >= n + 1) return 0;
				if (!st[j])
				{
					q[tt ++ ] = j;
					if (tt == N) tt = 0;
					st[j] = 0;
				}
			}
		}
	}
	
	return 1;
}

int main()
{
	cin >> n >> m;
	memset(h, -1, sizeof h);
	while (m -- )
	{
		int a, b, c;
		cin >> a >> b >> c;
		add(a, b, -c); // longest way
		add(0, a, 0);
		add(0, b, 0);
	}
	for (int i = 1; i <= n; i ++ ) add(0, i, 0);
	
	if (!spfa()) cout << "NO SOLUTION";
	else
	{
		for (int i = 1; i <= n; i ++ ) cout << dist[i] << endl;
	}
	
	return 0;
}