Submission #738198

#	Time	Username	Problem	Language	Result	Execution time	Memory
738198		GrindMachine	Valley (BOI19_valley)	C++17	100 / 100	766 ms	84000 KiB

valley

// Om Namah Shivaya

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x, y) ((x + y - 1) / (y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl

#define rep(i, n) for(int i = 0; i < n; ++i)
#define rep1(i, n) for(int i = 1; i <= n; ++i)
#define rev(i, s, e) for(int i = s; i >= e; --i)
#define trav(i, a) for(auto &i : a)

template<typename T>
void amin(T &a, T b) {
    a = min(a, b);
}

template<typename T>
void amax(T &a, T b) {
    a = max(a, b);
}

#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif

/*



*/

const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;

struct suffmx {
    // https://usaco.guide/adv/springboards?lang=cpp
    map<ll, ll> mp;

    void insert(pll p) {
        auto [x, y] = p;

        auto it = mp.lower_bound(x);
        if (it != mp.end() and it->second >= y) {
            return;
        }

        mp[x] = y;
        it = mp.find(x);

        if (it != mp.begin()) {
            it--;
            vector<ll> toerase;

            for (; y >= it->second; --it) {
                toerase.pb(it->first);
                if (it == mp.begin()) break;
            }

            trav(i, toerase) {
                mp.erase(i);
            }
        }
    }

    ll query(ll x) {
        auto it = mp.lower_bound(x);
        if (it == mp.end()) return -inf2;
        return it->second;
    }
};

vector<array<ll, 3>> adj[N];
vector<ll> edge_node(N);
vector<ll> tin(N), tout(N);
vector<ll> node_tin(N, -1);
ll timer = 1;

void dfs(ll u, ll p) {
    tin[u] = timer++;
    node_tin[tin[u]] = u;

    for (auto [v, w, id] : adj[u]) {
        if (v == p) conts;
        edge_node[id] = v;
        dfs(v, u);
    }

    tout[u] = timer - 1;
}

vector<ll> par(N, -1);
vector<bool> rem(N);
vector<ll> subsiz(N);

ll get_siz(ll u, ll p) {
    subsiz[u] = 1;

    for (auto [v, w, id] : adj[u]) {
        if (v == p or rem[v]) conts;
        subsiz[u] += get_siz(v, u);
    }

    return subsiz[u];
}

ll get_centroid(ll u, ll p, ll nodes) {
    for (auto [v, w, id] : adj[u]) {
        if (v == p or rem[v]) conts;
        if (subsiz[v] > nodes / 2) {
            return get_centroid(v, u, nodes);
        }
    }

    return u;
}

vector<ll> centroid_dis[N];

void dfs_dis(ll u, ll p, ll d) {
    centroid_dis[u].pb(d);
    for (auto [v, w, id] : adj[u]) {
        if (v == p or rem[v]) conts;
        dfs_dis(v, u, d + w);
    }
}

void build(ll u, ll p) {
    ll nodes = get_siz(u, -1);
    ll centroid = get_centroid(u, -1, nodes);

    par[centroid] = p;
    rem[centroid] = 1;
    dfs_dis(centroid, -1, 0);

    for (auto [v, w, id] : adj[centroid]) {
        if (rem[v]) conts;
        build(v, centroid);
    }
}

void solve(int test_case)
{
    ll n, s, q; cin >> n >> s >> q;
    ll root; cin >> root;

    rep1(i, n - 1) {
        ll u, v, w; cin >> u >> v >> w;
        adj[u].pb({v, w, i}), adj[v].pb({u, w, i});
    }

    vector<bool> spl(n + 5);
    rep1(i, s) {
        ll u; cin >> u;
        spl[u] = 1;
    }

    dfs(root, -1);
    build(root, -1);

    vector<array<ll, 3>> queries[n + 5];
    vector<suffmx> smx(n + 5);

    rep1(i, q) {
        ll edge, src; cin >> edge >> src;
        ll sub = edge_node[edge];
        ll l = tin[sub], r = tout[sub];
        queries[r].pb({edge, src, i});
    }

    vector<ll> ans(q + 5);

    rep1(t, n) {
        ll u = node_tin[t];
        if (u != -1 and spl[u]) {
            ll lca = u;
            auto &dis = centroid_dis[u];
            ll ptr = sz(dis) - 1;

            while (lca != -1) {
                ll d = dis[ptr--];
                smx[lca].insert({tin[u], -d});
                lca = par[lca];
            }
        }

        for (auto [edge, src, qid] : queries[t]) {
            ll sub = edge_node[edge];
            ll l = tin[sub], r = tout[sub];

            if (!(tin[src] >= l and tout[src] <= r)) {
                ans[qid] = -1;
                conts;
            }

            if (spl[src]) {
                ans[qid] = 0;
                conts;
            }

            ll lca = src;
            ll best = inf2;
            auto &dis = centroid_dis[src];
            ll ptr = sz(dis) - 1;

            while (lca != -1) {
                ll d = dis[ptr--];

                if (tin[lca] >= l and tout[lca] <= r) {
                    ll mn = -smx[lca].query(l);
                    if (mn < inf2) {
                        amin(best, d + mn);
                    }
                }

                lca = par[lca];
            }

            ans[qid] = best;
        }
    }

    rep1(i, q) {
        if (ans[i] == -1) {
            cout << "escaped" << endl;
        }
        else if (ans[i] >= inf2) {
            cout << "oo" << endl;
        }
        else {
            cout << ans[i] << endl;
        }
    }
}

int main()
{
    fastio;

    int t = 1;
    // cin >> t;

    rep1(i, t) {
        solve(i);
    }

    return 0;
}

Compilation message (stderr)

valley.cpp: In function 'void solve(int)':
valley.cpp:193:12: warning: unused variable 'l' [-Wunused-variable]
  193 |         ll l = tin[sub], r = tout[sub];
      |            ^

• Subtask 1: 9 / 9
• Subtask 2: 27 / 27
• Subtask 3: 23 / 23
• Subtask 4: 41 / 41