Submission #1125437

#	Time	Username	Problem	Language	Result	Execution time	Memory
1125437		NguyenPhucThang	Valley (BOI19_valley)	C++20	23 / 100	197 ms	43664 KiB

valley

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef vector<int> vi;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
typedef vector<pair<int, int>> vii;
typedef pair<int, pair<int, int>> piii;

#define forr(i, a, b) for (int i = (a); i <= (b); i++)
#define ford(i, a, b) for (int i = (a); i >= (b); i--)
#define forf(i, a, b) for (int i = (a); i < (b); i++)
#define fi first
#define se second
#define pb push_back
#define all(v) v.begin(), v.end()
#define mask(i) (1LL << (i))
#define bit(x, i) (((x) >> (i)) & 1)
#define bp __builtin_popcountll
#define file "test"

template<class X, class Y>
    bool minz(X &x, const Y &y) {
        if (x > y) {
            x = y;
            return true;
        } return false;
    }
template<class X, class Y>
    bool maxz(X &x, const Y &y) {
        if (x < y) {
            x = y;
            return true;
        } return false;
    }

const int base = 31;
const ll mod = 1e9 + 7; // 998244353;
const ll oo = (ll) 1e16;
const int N = 1e5 + 5;


bool isShop[N];
vii g[N];
int h[N], up[N][25];
ll magic[N], min_magic[N][25], cnt[N], dis[N];

struct Edge{
    int u, v;
} edge[N];

void dfs(int u, int pre) {
    for(pii e : g[u]) {
        int v = e.fi, w = e.se;
        if (v == pre) continue;
        h[v] = h[u] + 1;
        dis[v] = dis[u] + ll(w);

        dfs(v, u);
    }
}

void dfs2(int u, int pre) {
    for(pii e : g[u]) {
        int v = e.fi;
        if (v == pre) continue;
        up[v][0] = u;
        forr(j, 1, 19) up[v][j] = up[up[v][j - 1]][j - 1];
        dfs2(v, u);
    }
    min_magic[u][0] = magic[u];
    forr(j, 1, 19) min_magic[u][j] = min(min_magic[u][j - 1], min_magic[up[u][j - 1]][j - 1]);
}

int lca(int u, int v) {
    if (h[u] != h[v]) {
        if (h[u] < h[v]) swap(u, v);
        int k = h[u] - h[v];
        for(int j = 0; (1 << j) <= k; j++) if (bit(k, j)) u = up[u][j];
    }

    if (u == v) return u;

    int k = __lg(h[u]);
    ford(j, k, 0) if (up[u][j] != up[v][j]) u = up[u][j], v = up[v][j];
    return up[u][0];
}

void buildMagic(int u, int pre) {
    if (isShop[u]) magic[u] = dis[u], cnt[u] = 1;
    else magic[u] = oo, cnt[u] = 0;

    for(pii e : g[u]) {
        int v = e.fi;
        if (v == pre) continue;
        buildMagic(v, u);
        minz(magic[u], magic[v]);
        cnt[u] += cnt[v];
    }
}


ll jump(int u, int k) {
    ll res = oo;
    for(int j = 0; (1 << j) <= k; j++){
        if (bit(k, j)) {
            minz(res, min_magic[u][j]);
            u = up[u][j];
        }
    }

    return min(res, magic[u]);
}

int main(){
   ios_base::sync_with_stdio(0);
   cin.tie(0);


    int n, s, q, E;
    cin >> n >> s >> q >> E;

    forf(i, 1, n) {
        int x, y, w;
        cin >> x >> y >> w;
        g[x].pb({y, w});
        g[y].pb({x, w});
        edge[i] = {x, y};
    }

    forr(i, 1, s) {
        int x;
        cin >> x;
        isShop[x] = true;
    }


    dfs(E, E);
    forf(i, 1, n) if (h[edge[i].u] > h[edge[i].v]) swap(edge[i].u, edge[i].v);
    buildMagic(E, E);

    forr(i, 1, n) magic[i] = magic[i] - 2 * dis[i];
    dfs2(E, E);


    while (q--) {
        int I, R;
        cin >> I >> R;
        int u = edge[I].u, v = edge[I].v;
        if (lca(v, R) == v){
            if (cnt[v] == 0) cout << "oo\n";
            else {
                cout << dis[R] + jump(R, h[R] - h[v]) << '\n';
            }
        }
        else cout << "escaped\n";
    }


    return 0;
}

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