Submission #687521

#	Time	Username	Problem	Language	Result	Execution time	Memory
687521		stanislavpolyn	Valley (BOI19_valley)	C++17	36 / 100	3069 ms	17288 KiB

valley

#include <bits/stdc++.h>

#define fr(i, a, b) for (int i = (a); i <= (b); ++i)
#define rf(i, a, b) for (int i = (a); i >= (b); --i)
#define fe(x, y) for (auto& x : y)

#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define mt make_tuple

#define all(x) (x).begin(), (x).end()
#define pw(x) (1LL << (x))
#define sz(x) (int)(x).size()

using namespace std;

mt19937_64 rng(228);

#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template <typename T>
using oset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define fbo find_by_order
#define ook order_of_key

template <typename T>
bool umn(T& a, T b) {
    return a > b ? a = b, 1 : 0;
}
template <typename T>
bool umx(T& a, T b) {
    return a < b ? a = b, 1 : 0;
}

using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
template <typename T>
using ve = vector<T>;

const int N = 1e5 + 5;

int n, s, q, root;
ve<pii> g[N];
int w[N];
int p[N], pe[N];
int tin[N], tout[N], timer;
int who[N];
ll dep[N];
bool mark[N];
ll dp[N];

void dfs(int v = root, int p = 0) {
    ::p[v] = p;
    tin[v] = timer++;

    if (mark[v]) {
        dp[v] = 0;
    } else {
        dp[v] = 1e18;
    }

    fe (to, g[v]) {
        if (to.fi == p) continue;
        dep[to.fi] = w[to.se] + dep[v];
        who[to.se] = to.fi;
        pe[to.fi] = to.se;
        dfs(to.fi, v);

        umn(dp[v], dp[to.fi] + w[to.se]);
    }
    tout[v] = timer;
}

bool isUpper(int a, int b) {
    return tin[a] <= tin[b] && tout[a] >= tout[b];
}

int main() {
#ifdef LOCAL
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#else
    ios::sync_with_stdio(0);
    cin.tie(0);
#endif

    cin >> n >> s >> q >> root;

    fr (i, 1, n - 1) {
        int a, b;
        cin >> a >> b >> w[i];

        g[a].pb({b, i});
        g[b].pb({a, i});
    }

    fr (i, 1, s) {
        int x;
        cin >> x;
        mark[x] = 1;
    }

    dfs();

    fr (i, 1, q) {
        int idx, v;
        cin >> idx >> v;

        int u = who[idx];

        if (!isUpper(u, v)) {
            cout << "escaped\n";
        } else {
            int cur = v;
            ll best = 1e18;
            ll len = 0;
            while (1) {
                umn(best, len + dp[cur]);
                if (cur == u) {
                    break;
                }
                len += w[pe[cur]];
                cur = p[cur];
            }

            if (best == 1e18) {
                cout << "oo\n";
            } else {
                cout << best << "\n";
            }
        }
    }

    return 0;
}

• Subtask 1: 9 / 9
• Subtask 2: 27 / 27
• Subtask 3: 0 / 23
• Subtask 4: 0 / 41