Submission #940727

#	Time	Username	Problem	Language	Result	Execution time	Memory
940727		KK_1729	Evacuation plan (IZhO18_plan)	C++17	100 / 100	1020 ms	141584 KiB

plan

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

#define int long long
#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define pb push_back
#define all(a) a.begin(), a.end()
#define endl "\n"

void printVector(vector<int> a){
    for (auto x: a) cout << x << " ";
    cout << endl;
}

int N = 0;
vector<vector<pair<int, int>>> graph;
vector<int> distance(vector<int> source){
    // return ;
    using T = pair<long long, int>;
	priority_queue<T, vector<T>, greater<T>> pq; // stores dist, node
 
    vector<int> dist(N+1, 1e16);
    
 
    for (auto x: source){
        pq.push({0, x});
        dist[x] = 0;
    }
 
    while (!pq.empty()){
        auto [cdist, node] = pq.top();
 
        pq.pop();
        if (cdist != dist[node]) continue;
        for (auto x: graph[node]){
            if (cdist + x.second < dist[x.first]){
                pq.push({dist[x.first] = cdist + x.second, x.first});
            }
        }
    }
    return dist;
}


struct UFDS {
    vector<int> link, siz;
    UFDS(int n) : link(n), siz(n, 1) { iota(link.begin(), link.end(), 0); } //each element as its own subset, with size 1
    int findRoot(int x) {
        return x == link[x]  ? x : link[x]  =  findRoot(link[x]);  
    }
    bool same(int x, int y) { return findRoot(x) == findRoot(y); }
    bool unite(int x, int y) {
        x = findRoot(x);
        y = findRoot(y);
        if (x == y)
            return false;
        if (siz[x] < siz[y]) swap(x, y);
        siz[x] += siz[y];
        link[y] = x;
        return true;
    }
    int size(int x) { return siz[findRoot(x)]; }
};
int min(int x, int y){
    if (x < y) return x;
    else return y;
}
vector<vector<pair<int, int>>> maxtree;
vector<int> up(N+1);
int L = 0;
vector<vector<int>> bin;
vector<vector<int>> mbin;
vector<int> depth;

int lca(int a, int b){
    if (depth[a] < depth[b]) swap(a, b);
    int k = depth[a]-depth[b];
    for (int j = L-1; j >= 0; j--){
        if (k & (1 << j)) a = bin[a][j];
    }
    if (a == b) return a;
    for (int j = L-1; j >= 0; j--){
        if (bin[a][j] != bin[b][j]){
            a = bin[a][j];
            b = bin[b][j];
        }
    }
    return bin[a][0];
}
void solve(){
    int n, m; cin >> n >> m;
    N = n;
    graph.resize(n+1);

    FOR(i,0,m){
        int a, b, w; cin >> a >> b >> w;
        graph[a].pb({b, w});
        graph[b].pb({a, w});
    }

    int k; cin >> k;
    vector<int> np(k);
    FOR(i,0,k) cin >> np[i];

    vector<int> d = distance(np);

    vector<vector<int>> new_graph(n+1);
    vector<vector<int>> edges;
    FOR(i,1,n+1){
        for (auto x: graph[i]){
            edges.pb({min(d[x.first], d[i]), i, x.first});
        }
    }

    UFDS ds(n+1);
    sort(all(edges));
    reverse(all(edges));
    


    maxtree.resize(n+1);
    for (auto edge: edges){
        // printVector(edge);
        if (!ds.same(edge[1], edge[2])){
            // cout << edge[1] << " " << edge[2] << " " << edge[0] << endl;
            ds.unite(edge[1], edge[2]);
            maxtree[edge[1]].pb({edge[2], edge[0]});
            maxtree[edge[2]].pb({edge[1], edge[0]});
        }
    }
    // FOR(i,1,n+1){
    //     for (auto x: maxtree[i]) cout << x.first << x.second << endl;
    //     cout << endl;
    // }
    L = log2(n)+1;
    bin.resize(n+1, vector<int>(L+1));
    mbin.resize(n+1, vector<int>(L+1));
    depth.resize(n+1);
    stack<int> s;
    s.push(1);
    vector<int> vis(n+1);
    bin[1][0] = 1;
    depth[1] = 1;
    while (!s.empty()){
        int current = s.top();
        s.pop();
        if (vis[current]) continue;
        for (auto x: maxtree[current]){
            if (vis[x.first]) continue;
            bin[x.first][0] = current;
            mbin[x.first][0] = x.second;
            depth[x.first] = depth[current]+1;
            s.push(x.first);
        }
        vis[current] = 1;
    }
    for (int i = 1; i <= L; ++i){
        for (int j = 1; j <= n; ++j){
            bin[j][i] = bin[ bin[j][i-1] ][i-1];
            mbin[j][i] = min(mbin[j][i-1], mbin[ bin[j][i-1] ][i-1]);
        }
    }
    int q; cin >> q;
    while (q--){

        int a, b; cin >> a >> b;
        int l = lca(a, b);
        int k = depth[a]-depth[l];
        int ans = 1e16;
        for (int i = L; i >= 0; i--){
            if (k & (1 << i)){
                ans = min(ans, mbin[a][i]);
                a = bin[a][i];
            }
        }
        k = depth[b]-depth[l];
        for (int i = L; i >= 0; i--){
            if (k & (1 << i)){
                ans = min(ans, mbin[b][i]);
                b = bin[b][i];
            }
        }
        cout << ans << endl;
    }
}
int32_t main(){
    ios::sync_with_stdio(false);cin.tie(0);
    int t = 1; // cin >> t;
    while (t--) solve();
}

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