Submission #378614

#	Time	Username	Problem	Language	Result	Execution time	Memory
378614		wiwiho	Evacuation plan (IZhO18_plan)	C++14	100 / 100	862 ms	70368 KiB

plan

#include <bits/stdc++.h>

#define mp make_pair
#define F first
#define S second
#define eb emplace_back
#define printv(a, b) { \
    for(auto pv : a) b << pv << " "; \
    b << "\n"; \
}

using namespace std;

typedef long long ll;

using pll = pair<ll, ll>;
using pii = pair<int, int>;

const ll MAX = 1LL << 60;

ostream& operator<<(ostream& o, pll p){
    return o << '(' << p.F << ',' << p.S << ')';
}

ll iceil(ll a, ll b){
    return (a + b - 1) / b;
}

vector<int> dsu;
vector<vector<int>> g;
vector<ll> dvw;
int dv;

void initDSU(int n){
    dsu.resize(n + 1);
    for(int i = 1; i <= n; i++) dsu[i] = i;
}

int findDSU(int a){
    if(dsu[a] != a) dsu[a] = findDSU(dsu[a]);
    return dsu[a];
}

void unionDSU(int a, int b, ll w){
    a = findDSU(a);
    b = findDSU(b);
    if(a == b) return;
    int id = dv++;
    g[id].eb(a);
    g[id].eb(b);
    dsu[a] = id;
    dsu[b] = id;
    dvw[id] = w;
}

vector<vector<int>> anc;
vector<int> in, out;
int ts = 0;

void dfs(int now, int p){
    anc[now][0] = p;
    in[now] = ts++;
    for(int i : g[now]){
        dfs(i, now);
    }
    out[now] = ts++;
}

bool isAnc(int a, int b){
    return in[a] <= in[b] && out[a] >= out[b];
}

int lca(int a, int b){
    if(isAnc(a, b)) return a;
    for(int i = 19; i >= 0; i--){
        if(!isAnc(anc[a][i], b)) a = anc[a][i];
    }
    return anc[a][0];
}

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    
    int n, m;
    cin >> n >> m;
    dv = n + 1;

    vector<vector<pll>> tg(n + 1);
    for(int i = 0; i < m; i++){
        int u, v, w;
        cin >> u >> v >> w;
        tg[u].eb(mp(v, w));
        tg[v].eb(mp(u, w));
    }

    int k;
    cin >> k;
    vector<ll> dis(n + 1, MAX);
    priority_queue<pll, vector<pll>, greater<>> pq;
    for(int i = 0; i < k; i++){
        int t;
        cin >> t;
        dis[t] = 0;
        pq.push(mp(0, t));
    }
   
    while(!pq.empty()){
        int now = pq.top().S;
        ll d = pq.top().F;
        pq.pop();
        if(d != dis[now]) continue;
        for(pll i : tg[now]){
            if(dis[i.F] > d + i.S){
                dis[i.F] = d + i.S;
                pq.push(mp(d + i.S, i.F));
            }
        }
    }
    //printv(dis, cerr);

    vector<pll> v(n);
    for(int i = 0; i < n; i++) v[i] = mp(dis[i + 1], i + 1);
    sort(v.begin(), v.end(), greater<>());

    g.resize(2 * n);
    dvw.resize(2 * n);
    initDSU(2 * n - 1);

    vector<bool> ok(n + 1);
    for(pll i : v){
        int now = i.S;
        ok[now] = true;
        for(pll j : tg[now]){
            if(ok[j.F]) unionDSU(now, j.F, i.F);
        }
    }

    /*for(int i = 1; i < 2 * n; i++){
        cerr << i << "  ";
        printv(g[i], cerr);
    }
    printv(dvw, cerr);*/

    anc.resize(2 * n, vector<int>(20));
    in.resize(2 * n);
    out.resize(2 * n);

    int rt = findDSU(1);
    dfs(rt, rt);

    for(int i = 1; i < 20; i++){
        for(int j = 1; j < 2 * n; j++){
            anc[j][i] = anc[anc[j][i - 1]][i - 1];
        }
    }

    int q;
    cin >> q;
    while(q--){
        int a, b;
        cin >> a >> b;
        int t = lca(a, b);
        cout << dvw[t] << "\n";
    }

    return 0;
}

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