Submission #944463

#	Time	Username	Problem	Language	Result	Execution time	Memory
944463		AverageAmogusEnjoyer	Robot (JOI21_ho_t4)	C++17	0 / 100	3024 ms	18404 KiB

Main

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
template<class T> bool cmin(T &i, T j) { return i > j ? i=j,true:false; }
template<class T> bool cmax(T &i, T j) { return i < j ? i=j,true:false; }

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int n, m;
    cin >> n >> m;
    const ll inf = 1e18;
    vector<ll> weights(m+1);
    vector<map<int,vector<tuple<int,int,int>>>> adj(n);
    vector<map<int,pair<ll,int>>> dist_color(n); // min dist to node y 
                                              // while changing color c from node x: 
                                              // x -> y throught node c, I changed color
                                              // to node c
    for (int i=0,u,v,c;i<m;i++) {
        cin >> u >> v >> c >> weights[i];
        --u,--v,--c;
        adj[u][c].emplace_back(v,weights[i],i);
        adj[v][c].emplace_back(u,weights[i],i);
        if (u) { dist_color[u][c]=make_pair(inf,m); }
        if (v) { dist_color[v][c]=make_pair(inf,m); } 
    }
    weights[m]=-inf;
    vector<ll> dist(n,inf);
    dist[0] = 0;
    priority_queue<tuple<ll,int,int>> q;
    q.emplace(0,-1,0);


    // BRUH :(

    while(!q.empty()) {
        auto [d,last_changed,x] = q.top(); q.pop();
        if (last_changed == -1) {
            if (d > dist[x]) { continue; }
            // run pseudo-normal dijkstra
            for (auto &[color,_] : adj[x]) {
                int sz = (int)_.size();
                ll sum = 0;
                for (auto &[y,w,idx]: _) {
                    sum += w;
                }
                ll option = min(dist[x],
                        dist_color[x][color].first-weights[dist_color[x][color].second]); 
                for (auto &[y,w,idx]: _) {
                    if (idx == dist_color[x][color].second) { continue; }
                    if (sz == 1) {
                        if (cmin(dist[y],dist[x])) {
                            q.emplace(dist[y],-1,y);
                        }
                    } else {
                        // first option: I change this
                        if (cmin(dist[y],dist[x]+w)) {
                            if (cmin(dist_color[y][color].first,dist[x]+w)) {
                                dist_color[y][color].second=idx;
                            }
                            q.emplace(dist[y],-1,y);
                        } else if (cmin(dist_color[y][color].first,dist[x]+w)) {
                            dist_color[y][color].second=idx; 
                            q.emplace(dist[x]+w,color,y);
                        }
                        // second option: I change all others
                        ll now = sum-w+option;
                        if (cmin(dist[y],now)) {
                            q.emplace(now,-1,y);
                        }
                    }
                }
            }
        } else {
            if (d > dist_color[x][last_changed].first) { continue; } 
            int how_many = (int)adj[x][last_changed].size() - 1;
            ll second_option = dist_color[x][last_changed].first;
            for (auto &[y,w,idx]: adj[x][last_changed]) {
                second_option+=w;
            }
            second_option -= weights[dist_color[x][last_changed].second];
            for (auto &[y,w,idx]: adj[x][last_changed]) {
                if (idx == dist_color[x][last_changed].second) { continue; } 
                if (how_many == 1) {
                    ll tot=d;
                    if (cmin(dist[y],tot)) {
                        q.emplace(tot,-1,y);
                    }
                } else {
                    // first: change this one
                    ll tot=d+w;
                    if (cmin(dist[y],tot)) {
                        if (cmin(dist_color[y][last_changed].first,tot)) {
                            dist_color[y][last_changed].second=w;
                        }
                        q.emplace(tot,-1,y);
                    } else if (cmin(dist_color[y][last_changed].first,tot)) {
                        dist_color[y][last_changed].second=w;
                        q.emplace(tot,last_changed,y);
                    }
                    // second: change all the others
                    tot = second_option - w;
                    if (cmin(dist[y],tot)) {
                        q.emplace(tot,-1,y);
                    }
                }
            }   
        }
    }
    cout << (dist[n-1] == inf ? -1 : dist[n-1]) << endl;
}

• Subtask 1: 0 / 34
• Subtask 2: 0 / 24
• Subtask 3: 0 / 42