Submission #308194

#	Time	Username	Problem	Language	Result	Execution time	Memory
308194		HynDuf	Valley (BOI19_valley)	C++11	100 / 100	341 ms	38008 KiB

valley

#include <bits/stdc++.h>

#define task "V"
#define all(v) (v).begin(), (v).end()
#define rep(i, l, r) for (int i = (l); i <= (r); ++i)
#define Rep(i, r, l) for (int i = (r); i >= (l); --i)
#define DB(X) { cerr << #X << " = " << (X) << '\n'; }
#define DB1(A, _) { cerr << #A << "[" << _ << "] = " << (A[_]) << '\n'; }
#define DB2(A, _, __) { cerr << #A << "[" << _ << "][" << __ << "] = " << (A[_][__]) << '\n'; }
#define DB3(A, _, __, ___) { cerr << #A << "[" << _ << "][" << __ << "][" << ___ << "] = " << (A[_][__][___]) << '\n'; }
#define PR(A, l, r) { cerr << '\n'; rep(_, l, r) DB1(A, _); cerr << '\n';}
#define SZ(x) ((int)(x).size())
#define pb push_back
#define eb emplace_back
#define pf push_front
#define F first
#define S second
#define by(x) [](const auto& a, const auto& b) { return a.x < b.x; } // sort(arr, arr + N, by(a));
#define next ___next
#define prev ___prev
#define y1 ___y1
#define left ___left
#define right ___right
#define y0 ___y0
#define div ___div
#define j0 ___j0
#define jn ___jn

using ll = long long;
using ld = long double;
using ull = unsigned long long;
using namespace std;
typedef pair<int, int> ii;
typedef pair<ii, int> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<ll> vl;
const int N = 1e5 + 2;
const ll INF = 1e18;
int n, m, r, q, pa[N][18], dep[N];
bool market[N];
ll d[N], mn[N], mnA[N][18];
vii g[N];
ii edge[N];
void dfs(int u, int p)
{
    dep[u] = dep[p] + 1;
    pa[u][0] = p;
    rep(k, 1, 17) pa[u][k] = pa[pa[u][k - 1]][k - 1];
    mn[u] = INF;
    for (ii v : g[u]) if (v.F != p)
    {
        d[v.F] = d[u] + v.S;
        dfs(v.F, u);
        mn[u] = min(mn[u], mn[v.F]);
    }
    if (market[u]) mn[u] = min(mn[u], d[u]);
}
int lca(int x, int y)
{
    if (dep[x] < dep[y]) swap(x, y);
    Rep(k, 17, 0) if (dep[pa[x][k]] >= dep[y]) x = pa[x][k];
    if (x == y) return x;
    Rep(k, 17, 0) if (pa[x][k] != pa[y][k]) x = pa[x][k], y = pa[y][k];
    return pa[x][0];
}
void buildmnA(int u, int p)
{
    mnA[u][0] = mn[u];
    rep(k, 1, 17) mnA[u][k] = min(mnA[u][k - 1], mnA[pa[u][k - 1]][k - 1]);
    for (ii v : g[u]) if (v.F != p) buildmnA(v.F, u);
}
int main()
{
#ifdef HynDuf
    freopen(task".in", "r", stdin);
    //freopen(task".out", "w", stdout);
#else
    ios_base::sync_with_stdio(false); cin.tie(nullptr);
#endif
    cin >> n >> m >> q >> r;
    rep(i, 2, n)
    {
        int u, v, w;
        cin >> u >> v >> w;
        g[u].eb(v, w);
        g[v].eb(u, w);
        edge[i - 1] = {u, v};
    }
    rep(i, 1, m)
    {
        int u;
        cin >> u;
        market[u] = 1;
    }
    dfs(r, 0);
    rep(i, 1, n) if (mn[i] != INF) mn[i] -= 2 * d[i];
    buildmnA(r, 0);
    while (q--)
    {
        int e, u, uu;
        cin >> e >> u;
        uu = u;
        int v = (dep[edge[e].F] > dep[edge[e].S]) ? edge[e].F : edge[e].S;
        if (lca(u, v) != v) cout << "escaped\n";
        else
        {
            ll ans = mn[v];
            Rep(k, 17, 0) if (dep[pa[u][k]] >= dep[v])
            {
                ans = min(ans, mnA[u][k]);
                u = pa[u][k];
            }
            if (ans == INF) cout << "oo\n";
            else cout << ans + d[uu] << '\n';
        }
    }
    return 0;
}

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