Submission #703575

#	Time	Username	Problem	Language	Result	Execution time	Memory
703575		bebra	Valley (BOI19_valley)	C++17	36 / 100	3045 ms	10052 KiB

valley

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

#define int long long

#define dbg(x) cerr << #x << ": " << x << endl;


const int MAX_N = 1e5 + 5;
const ll INF = 1e17;
vector<tuple<int, ll, int>> g[MAX_N];
bool special[MAX_N];
ll dp[MAX_N];
bool used[MAX_N];

int t;
bool found = false;


void dfs(int v, int p, int edge) {
    if (special[v]) {
        dp[v] = 0;
    } else {
        dp[v] = INF;
    }
    if (v == t) {
        found = true;
    }
    for (const auto& [u, w, idx] : g[v]) {
        if (idx == edge) continue;
        if (u == p) continue;
        dfs(u, v, edge);
        dp[v] = min(dp[v], dp[u] + w);
    }
}


int32_t main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, s, q;
    cin >> n >> s >> q >> t;
    --t;

    for (int i = 0; i < n - 1; ++i) {
        int u, v;
        cin >> u >> v;
        --u, --v;
        int w;
        cin >> w;
        g[u].emplace_back(v, w, i);
        g[v].emplace_back(u, w, i);
    }

    for (int i = 0; i < s; ++i) {
        int v;
        cin >> v;
        --v;
        special[v] = true;
    }


    while (q--) {
        int edge, r;
        cin >> edge >> r;
        --edge, --r;
        found = false;
        dfs(r, -1, edge);

        if (found) {
            cout << "escaped\n";
            continue;
        }
        if (dp[r] == INF) {
            cout << "oo\n";
        } else {
            cout << dp[r] << '\n';
        }
    }

    return 0;
}


/*
5 2 3 4

1 2 1
2 3 1
3 4 1
4 5 1

1 5

4 4
2 4
2 3


*/

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