4 контест 3 задача

#include <iostream>
#include<vector>
#include<algorithm>
#include <iomanip>

using namespace std;

vector<vector<pair<int, double>>> G;
vector<int> used;
vector<double> variability;
int n;

void dkstr(int v) {
    variability[v] = 1;
    for (int i = 0; i < n; i++) {
        //поиск минимума
        int max_v = -1;
        double max_ver = -1;
        for (int i = 0; i < n; i++) {
            if (used[i] == 0 && variability[i] > max_ver) {
                max_v = i;
                max_ver = variability[i];
            }
        }
        if (max_v == -1) {
            return;
        }
        //релаксация
        used[max_v] = 1;
        for (int i = 0; i < G[max_v].size(); i++) {
            int actual_v = G[max_v][i].first;
            double weight = G[max_v][i].second;
            if (used[actual_v] == 0 && variability[actual_v] < max_ver * weight) {
                variability[actual_v] = max_ver * weight;
            }
        }
    }
}

int main() {
    int m;
    cin >> n >> m;
    int s, f;
    cin >> s >> f;
    s -= 1;
    f -= 1;

    G = vector<vector<pair<int, double>>>(n);
    used = vector<int>(n);
    variability = vector<double>(n, -1);

    //ввод данных
    for (int i = 0; i < m; i++) {
        int fr, to, ver;
        cin >> fr >> to >> ver;
        fr--;
        to--;
        G[fr].push_back(make_pair(to, 1 - double(ver) / 100));
        G[to].push_back(make_pair(fr, 1 - double(ver) / 100));
    }

    dkstr(s);

    if (used[f] == 0) {
        cout << -1;
    } else {
        cout << fixed << 1 - variability[f] << '\n';
    }
    return 0;
}