C++

#include <bits/stdc++.h>
#define endl "\n"
using namespace std;
int n, m, a, b;
double dis[100001];
vector <int> ph[100001]; // 出边序号
vector <int> pv[100001]; // 出边汇率

void dijkstra(int s)
{
	bool vis[100001] = {};
	memset(dis, 0, sizeof dis);
	dis[s] = 1;
	priority_queue <pair <double, int> > pq;
//	priority_queue <pair <double, int>, vector <pair <double, int> >, greater <pair <double, int> > > pq;
	pq.push({1, s});
	while (! pq.empty())
	{
		auto t = pq.top();
		pq.pop();
		int v = t.second;
		if (vis[v])
			continue;
		vis[v] = true;
		for (int i = 0; i < ph[v].size(); i ++)
		{
			int j = ph[v][i];
			if (dis[j] < dis[v] * (1 - pv[v][i] / 100.0))
			{
				dis[j] = dis[v] * (1 - pv[v][i] / 100.0);
				pq.push({dis[j], j});
			}
		}
	}
	for (int i = 1; i <= n; i ++)
	{
		if (dis[i] == 0x3f3f3f3f)
			dis[i] = INT_MAX;
	}
}

int main()
{
	ios :: sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	cin >> n >> m;
	for (int i = 1; i <= m; i ++)
	{
		int u, v, w;
		cin >> u >> v >> w;
		if (u == v)
			continue;
		ph[u].push_back(v);
		pv[u].push_back(w);
	}
	cin >> a >> b;
	dijkstra(a);
	cout << fixed << setprecision(8) << 100 / dis[b] << endl;
	return 0;
}