一本通 1344【最短路】

#pragma GCC optimize(3, "Ofast", "inline")
#include 

using namespace std;

const int N = 2e5 + 10;
vector <pair <int, double> > z[N];
double dis[N];
int id[N];
bool inque[N];
int n, p, cc, m;

void spfa(int s)
{
  memset (dis, 0x7f, sizeof dis);
  dis[s] = 100;
  queue <int> q;
  q.push(s);
  inque[s] = true;
  while (q.size())
  {
    int f = q.front();
    q.pop();
    inque[f] = false;
    for (auto &u : z[f])
      if (dis[u.first] > dis[f] * 100. / (100. - u.second))
      {
        dis[u.first] = dis[f] * 100. / (100. - u.second);
        if (!inque[u.first])
        {
          inque[u.first] = true;
          q.push(u.first);
        }
      }
  }
}

signed main()
{
  cin >> n >> m;
  for (int i = 1; i <= m; i ++)
  {
    int a, b, c;
    cin >> a >> b >> c;
    z[a].push_back(make_pair(b, c));
    z[b].push_back(make_pair(a, c));
  }
  int a, b;
  cin >> a >> b;
  spfa(b);
  printf ("%.8lf\n", dis[a]);
}

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