找了不少帖子，发现大家的思路都很好，但对于我这个AcWing的小白来说还是有点难以理解，这里把自己琢磨的AC代码分享出来，学了AcWing算法基础课的朋友应该可以看的更轻松。

//朴素版本

#include<bits/stdc++.h>
using namespace std;
const int N = 2010;
const int M = 1e5+10;
int e[M],ne[M],h[N],idx;
double w[M];
int n,m,A,B;
int state[N];
double dist[N];

void add(int k,int x,double y)
{
    e[idx] = x, w[idx] = 1-y*0.01, ne[idx] = h[k], h[k] = idx++;
}

void diji()
{
    fill(dist,dist+1+N,0);
    dist[A] = 1;
    for(int i = 1;i <=n;i++)
    {
        int t = -1;
        for(int j = 1;j <=n;j++)
        {
            if(!state[j] && (t == -1 || dist[j] > dist[t]))
                t = j;
        }
        //cout << t<<endl;
        if(t == -1)return;
        state[t] = 1;
        for(int k = h[t];k != -1;k = ne[k])
        {
            int j = e[k];
            dist[j] = max(dist[j],dist[t]*w[k]);
            // cout << t<<endl;
        }
    }
}

int main()
{
    memset(h,-1,sizeof h);
    cin >> n >> m;
    while(m--)
    {
        int a,b;
        double c;
        cin >> a >> b >> c;
        add(a,b,c);
        add(b,a,c);
    }
    cin >> A >> B;
    if(A>B)swap(A,B);
    diji();
    // cout << dist[n] << endl;
    //for(int i = 1;i<=n;i++)cout <<fixed<<setprecision(8)<< w[i]<<endl;
    //cout << dist[B] << endl;
    cout <<fixed<<setprecision(8)<< 100/dist[B];
}

//堆优化版本

#include<bits/stdc++.h>
using namespace std;
const int N = 2010;
const int M = 2e5+10;

int e[M],ne[M],h[N],idx;
int state[N];
double dist[N],w[M];
int n,m,A,B;
typedef pair<double,int> PII;
priority_queue <PII> heap;//distance,ver

void add(int k,int x,double y)
{
    e[idx] = x, w[idx] = 1-y*0.01, ne[idx] = h[k], h[k] = idx++;
}

void diji()
{
    fill(dist,dist+1+N,0);
    dist[A] = 1;
    heap.push({1,A});
    while(heap.size())
    {
        PII t = heap.top();
        heap.pop();
        int ver = t.second;
        if(state[ver]) continue;
        else state[ver] = 1;
        for(int i = h[ver]; i != -1;i = ne[i])
        {
            int j = e[i];
            if(dist[j] < dist[ver]*w[i])
            {
                dist[j] = dist[ver]*w[i];
                heap.push({dist[j],j});
            }
        }
    }
}

int main()
{
    memset(h,-1,sizeof h);
    cin >> n >> m;
    while(m--)
    {
        int a,b;
        double c;
        cin >> a >> b >> c;
        add(a,b,c);
        add(b,a,c);
    }
    cin >> A >> B;
    if(A>B)swap(A,B);
    diji();
    //for(int i = 1;i<=n;i++)cout <<fixed<<setprecision(8)<< w[i]<<endl;
    //cout << dist[B] << endl;
    cout <<fixed<<setprecision(8)<< 100/dist[B];
    
    return 0;
}