4 контест 3 задача

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

using namespace std;

int n;
vector<vector<pair<int, double>>> g;
vector<bool> used;
vector<double> probability;

void dijkstra(int start = 0) {
    probability[start] = 1;
    for (int i = 0; i < n; i++) {
        // n итераций
        int max_v = -1;
        double max_value = 0;
        for (int j = 0; j < n; j++) {
            if (probability[j] >= max_value && !used[j]) {
                max_v = j;
                max_value = probability[j];
            }
        }
        if (max_v == -1)
            return;
        used[max_v] = true;
        for (auto &j: g[max_v]) {
            probability[j.first] = max(probability[max_v] * j.second, probability[j.first]);
        }
    }
}


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

    g = vector<vector<pair<int, double>>>(n);
    probability = vector<double>(n, 0);
    used = vector<bool>(n);

    for (int i = 0; i < m; i++){
        int fr, to;
        double value;
        cin >> fr >> to >> value;
        fr--;to--;
        g[fr].emplace_back(to, 1 - value / 100);
        g[to].emplace_back(fr, 1 - value / 100);
    }

    dijkstra(s);

    if (!used[f])
        cout << -1;
    else
        cout << fixed << 1 - probability[f];


    return 0;
}