这代码有神马问题吗？

#include<bits/stdc++.h>
using namespace std;
int n, m, ans = 1e9, cn[101];
struct tu{int u, w;}v[101][2002];
bool vis[101];
void dfs (int d, int cnt, int ma)
{
	if (cnt > ans)return;
	if (d == n){ans = min (ans, cnt + ma);return;}
	for (int i = 0; i < cn[d]; ++ i)
	{
		if (! vis[d])
		{
			vis[d] = 1;
			dfs (v[d][i].u, cnt + v[d][i].w, max (ma, v[d][i].w));
			vis[d] = 0;
		}
	}
}
signed main()
{
	scanf ("%d %d", &n, &m);
	for (int i = 0; i < m; ++ i)
	{
		int a, b, c;
		scanf ("%d %d %d", &a, &b, &c);
		tu d;
		d.u = b;
		d.w = c;
		v[a][cn[a] ++] = d;
		d.u = a;
		v[b][cn[b] ++] = d;
	}
	dfs (1, 0, 0);
	printf ("%d", ans);
	return 0;
}

啊啊啊，就40分