求助，悬关 写的跟第一篇TJ差不多，但线段树这边RE了，也不排除是别的地方的问题

#include <bits/stdc++.h>

using namespace std;

const int N = 100010, M = 400010, INF = 0x3f3f3f3f;
typedef pair<int, int> PII;

int n, m;
int h[N], e[M], w[M], ne[M], idx;
int l[N], r[N], id[N], path[N];
int res[N], d[2][N];
bool st[N], o[M];
int q[N];

struct Node
{
	int l, r;
	int v;
}tr[N * 4];

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

void dijkstra(int start, int *d)
{
	memset(st, 0, sizeof st);
	for (int i = 1; i <= n; i ++ ) d[i] = INF; d[start] = 0;
	priority_queue<PII, vector<PII>, greater<PII> > heap; 
	heap.push({0, start});
	
	while (heap.size())
	{
		PII t = heap.top(); heap.pop();
		int ver = t.second, distance = t.first;
		if (st[ver]) continue ;
		st[ver] = true;
		for (int i = h[ver]; ~i; i = ne[i])
		{
			int j = e[i];
			if (d[j] > distance + w[i])
			{
				d[j] = distance + w[i];
				heap.push({d[j], j});
			}
		}
	}
}

void build(int u, int l, int r)
{
	tr[u] = {l, r, INF};
	if (l != r)
	{
		int mid = l + r >> 1;
		build(u << 1, l, mid), build(u << 1 | 1, mid + 1, r);
	}
}

void modify(int u, int l, int r, int v)
{
	if (tr[u].l >= l && tr[u].r <= r) { tr[u].v = min(tr[u].v, v); return ; }
	int mid = tr[u].l + tr[u].r >> 1;
	if (l <= mid) modify(u << 1, l, r, v);
	if (r > mid) modify(u << 1 | 1, l, r, v);
}

void update(int u)
{
	if (tr[u].l == tr[u].r)
	{
		res[tr[u].l] = tr[u].v;
		return ;
	}
	tr[u << 1].v = min(tr[u << 1].v, tr[u].v), tr[u << 1 | 1].v = min(tr[u << 1 | 1].v, tr[u].v);
	update(u << 1), update(u << 1 | 1);
}

void bfs(int p, int *d, int *a)
{
	int S = path[p]; a[S] = p;
	int hh = 0, tt = 0; q[0] = S;
	while (hh <= tt)
	{
		int t = q[hh ++ ];
		for (int i = h[t]; ~i; i = ne[i])
		{
			int j = e[i];
			if (!id[j] && !a[j] && d[j] == d[t] + w[i]) a[j] = t, q[ ++ tt] = j;
		}
	}
}

int main()
{
	memset(h, -1, sizeof h);
	scanf("%d%d", &n, &m);
	for (int i = 1; i <= m; i ++ )
	{
		int a, b, c;
		scanf("%d%d%d", &a, &b, &c);
		add(a, b, c), add(b, a, c);
	}
	dijkstra(1, d[0]); dijkstra(n, d[1]);
	
	int len = 0;
	int now = 1;
	while (now < n)
	{
		path[ ++ len] = now; id[now] = len;
		for (int i = h[now]; ~i; i = ne[i])
		{
			int j = e[i];
			if (d[1][j] + w[i] == d[1][now]) 
			{
				o[i] = true, now = j;
				break ;
			}
		}
	}
	path[ ++ len] = n, id[n] = len;
	for (int i = 1; i <= len; i ++ ) bfs(i, d[0], l), bfs(i, d[1], r);

	len -- ; build(1, 1, len);
	for (int u = 1; u <= n; u ++ )
		for (int i = h[u]; ~i; i = ne[i])
		{
			int j = e[i];
			if (!o[i] && l[u] < r[j]) modify(1, l[u], r[j] - 1, d[0][u] + w[i] + d[1][j]);
		}
	update(1);
	
	int maxv = 0, cnt = 0;
	for (int i = 1; i <= len; i ++ )
		if (res[i] > maxv) maxv = res[i], cnt = 1;
		else if (res[i] == maxv) cnt ++ ;
	if (maxv == d[0][n]) cnt = m;
	printf("%d %d\n", maxv, cnt);
	return 0;
}