把 output 递归也不好使

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
#include <map>
#include <queue>

#define x first
#define y second

using namespace std;

const int N = 3010, M = 20010;

int h[N], e[M], ne[M], idx; 
void add(int a, int b)
{
	e[ ++ idx] = b, ne[idx] = h[a], h[a] = idx;
}

struct Node
{
	int a, b, c;
	bool operator < (const Node &W)const
	{
		if (W.a != a) return W.a < a;
		if (W.b != b) return W.b < b;
		return W.c < c;
	}
};

map<Node, bool> Map;
int f[N][N];
int n, m, k;
queue<pair<int, int>> q;
int path[N];

void output(int u)
{
	int stk[N], top = 0;
	while (path[u]) stk[ ++ top] = u, u = path[u];
	while (top) printf("%d ", stk[top -- ]);
}

int main()
{
	scanf("%d%d%d", &n, &m, &k);
	
	while (m -- )
	{
		int a, b;
		scanf("%d%d", &a, &b);
		add(a, b), add(b, a);
	}
	
	for (int i = 1, a, b, c; i <= k; i ++ )
		scanf("%d%d%d", &a, &b, &c),
		Map[{a, b, c}] = true;
		
	q.push({0, 1});
	
	while (q.size())
	{
		auto t = q.front();
		q.pop();
		
		int a = t.x, b = t.y;
		
		for (int i = h[b]; i; i = ne[i])
		{
			int c = e[i];
			if (Map[{a, b, c}]) continue;
			if (f[b][c]) continue;
			path[c] = b;
			f[b][c] = f[a][b] + 1;
			q.push({b, c});
			
			if (c == n)
				output(n);
		}
	}
	
	return 0;
}