Submission #955415

#	Time	Username	Problem	Language	Result	Execution time	Memory
955415		ProtonDecay314	Cyberland (APIO23_cyberland)	C++17	15 / 100	3040 ms	7664 KiB

cyberland

#include "cyberland.h"

#include <vector>
#include <bits/stdc++.h>
using namespace std;

struct node {
    int i;
    int k;
    
    node(int a_i, int a_k): i(a_i), k(a_k) {};

    int get_ind() {
        return (i << 5) | k;
    }

    bool operator<(const node& other) const {
        return true;
    }
};

double solve(int N, int M, int K, int H, std::vector<int> x, std::vector<int> y, std::vector<int> c, std::vector<int> arr) {
    vector<vector<pair<int, int>>> adj;
    for(int i = 0; i < N; i++) {
        vector<pair<int, int>> adj_row;
        adj.push_back(adj_row);
    }

    for(int i = 0; i < M; i++) {
        int curx = x[i], cury = y[i], curc = c[i];

        adj[curx].push_back({cury, curc});
        adj[cury].push_back({curx, curc});
    }

    /*
    Initial BFS to find the reachable nodes
    */

    vector<bool> found(N, false);
    queue<int> bfs_q;
    bfs_q.push(0);

    while(!bfs_q.empty()) {
        int curq = bfs_q.front();
        bfs_q.pop();

        if(found[curq]) continue;
        found[curq] = true;

        for(auto [j, w] : adj[curq]) {
            bfs_q.push(j);
        }
    }

    /*
    Idea: Dijkstra's algorithm
    priority_queue<{total_time, node}>
    */
    double ans = numeric_limits<double>::max();

    priority_queue<pair<double, int>, vector<pair<double, int>>, greater<pair<double, int>>> q;

    vector<double> dist(N, 0.0);

    for(int k = 0; k <= K; k++) {
        vector<bool> vis(N, false);

        if(k == 0) {
            q.push({0.0, 0});
            for(int i = 1; i < N; i++) {
                if(arr[i] == 0 && found[i]) {
                    q.push({0.0, i});
                }
            }
        } else {
            q.push({0.0, 0});
            for(int i = 1; i < N; i++) {
                if(arr[i] == 0 && found[i]) {
                    q.push({0.0, i});
                }
                if(arr[i] == 2 && found[i]) {
                    double min_i_time = numeric_limits<double>::max();
                    for(auto [j, w] : adj[i]) {
                        min_i_time = min(min_i_time, dist[j] + (double)w);
                    }
                    q.push({min_i_time / 2.0, i});
                }
            }
        }
        while(! q.empty()) {
            auto [cur_time, i] = q.top();

            q.pop();

            if(vis[i]) continue;
            vis[i] = true;
            dist[i] = cur_time;

            if(i == H) {
                ans = min(ans, cur_time);
                continue;
            }

            for(auto [j, w] : adj[i]) {
                if(arr[j] == 1 || arr[j] == 2) {
                    q.push({cur_time + (double)w, j});
                }
            }
        }
    }

    if(ans < numeric_limits<double>::max()) {
        return ans;
    }

    return -1;
}

• Subtask 1: 0 / 5
• Subtask 2: 8 / 8
• Subtask 3: 0 / 13
• Subtask 4: 0 / 19
• Subtask 5: 7 / 7
• Subtask 6: 0 / 16
• Subtask 7: 0 / 29
• Subtask 8: 0 / 3