Submission #1209122

#	Time	Username	Problem	Language	Result	Execution time	Memory
1209122		lopkus	Evacuation plan (IZhO18_plan)	C++20	100 / 100	435 ms	73460 KiB

plan

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

#define int long long

const int maxn = 2e5 + 5;

//dsu rollback + parallel binary search

struct DSU{
    vector<pair<int, int>> past_p, past_sz;
    vector<int> st;
    int p[maxn], sz[maxn];
    void init(){
        for(int i = 1; i < maxn; i++){
            p[i] = i; 
            sz[i] = 1; 
        }
    }
    int find(int u){
        return (p[u] == u ? u : find(p[u]));
    }

    void unon(int a, int b){
        a = find(a); 
        b = find(b);
        if(sz[a] < sz[b]) swap(a, b);
        past_sz.push_back({a, sz[a]}); 
        past_p.push_back({b, p[b]}); 
        if(a != b){
            sz[a] += sz[b]; 
            p[b] = a;
        }
    }
    void rollback(){
        
    }
    void save(){
        st.push_back(past_p.size());
    }
    void to_last(){
        while(past_p.size() != st.back()){
            p[past_p.back().first] = past_p.back().second; 
            sz[past_sz.back().first] = past_sz.back().second; 
            past_p.pop_back();
            past_sz.pop_back();
        }
        st.pop_back();
    }
} dsu;

int ans[maxn], s[maxn], t[maxn], pos[maxn];
vector<pair<int, int>> adj[maxn];
vector<int> comp, all;

void solve(int l, int r, vector<int>& cur){
    if(l == r) for(int i: cur) ans[i] = l;
    else{
        dsu.save();
        int mid = (l + r) / 2;
        for(int i = l; i <= mid; i++){
            for(auto [v, w]: adj[comp[i]]){
                if(pos[v] <= mid) dsu.unon(comp[i], v);
            }
        }

        vector<int> le, ri;
        for(int i: cur){
            if(dsu.find(s[i]) == dsu.find(t[i])) le.push_back(i);
            else ri.push_back(i);
        }

        if(mid < r && ri.size()) solve(mid + 1, r, ri);
        
        dsu.to_last();

        if(le.size()) solve(l, mid, le);
    }
    
}
signed main(){
    ios_base::sync_with_stdio(false); 
    cin.tie(0); cout.tie(0);

    int n, m; cin >> n >> m;

    vector<int> d(n + 1, 1e9);

    for(int i = 1; i <= m; i++){
        int u, v, w; cin >> u >> v >> w;
        adj[u].push_back({v, w}); 
        adj[v].push_back({u, w});
    }

    int k; cin >> k;
    priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq; 

    for(int i = 0; i < k; i++){
        int x; cin >> x;
        d[x] = 0; 
        pq.push({0, x});
    }

    while(!pq.empty()){
        auto [curw, u] = pq.top(); 
        pq.pop();
        if(d[u] != curw) continue;
        for(auto [v, w]: adj[u]){
            if(d[v] > curw + w){
                d[v] = curw + w;
                pq.push({d[v], v});
            }
        }
    }

    for(int i = 1; i <= n; i++) comp.push_back(i);
    sort(comp.begin(), comp.end(), [&](int x, int y){
        return d[x] > d[y];
    });

    int q; cin >> q;
    for(int i = 0; i < q; i++){
        cin >> s[i] >> t[i];
        all.push_back(i);
    }
    for(int i = 0; i < n; i++) pos[comp[i]] = i;
    
    dsu.init();

    solve(0, n - 1, all);

    for(int i = 0; i < q; i++) cout << d[comp[ans[i]]] << "\n";
}

• Subtask 1: 10 / 10
• Subtask 2: 13 / 13
• Subtask 3: 12 / 12
• Subtask 4: 19 / 19
• Subtask 5: 46 / 46