Submission #1358101

#TimeUsernameProblemLanguageResultExecution timeMemory
1358101madamadam3봉쇄 시간 (IOI23_closing)C++20
8 / 100
161 ms58488 KiB
#include "closing.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
using pi = pair<ll, ll>;
using vi = vector<int>;
using vvi = vector<vi>;

template<class T> bool chmin(T& a, const T& b) {return b < a ? a = b, 1 : 0;}
template<class T> bool chmax(T& a, const T& b) {return a < b ? a = b, 1 : 0;}

#define rep(i,a,b) for (int i = a; i < b; i++)
#define rev(i,a,b) for (int i = a; i >= b; i--)
#define sz(x) ((int) (x).size())
#define bg(x) (x).begin()
#define en(x) (x).end()
#define all(x) bg(x), en(x)
#ifdef LOCAL
    #define dbg(x) cout << #x << " = " << x << "\n"
#else
    #define dbg(x)
#endif

/*
weighted edges denoting the time, given a fixed budget k, determine the max
Σ(1 if city[i] can be reached from node x) + Σ(1 if city[i] can be reached from node y)
where a node is reachable iff ct[i] >= Σ(edges on shortest path to i)
the graph is a tree
*/

const int MAXN = 200'000, MAXLOG = 19;
int n, m, timer = 0;
int tin[MAXN+5] = {}, tout[MAXN+5] = {}; ll dist_root[MAXN+5] = {};
vector<vector<pi>> G;
vvi up;

void dfs(int u, int p, ll d) {
    tin[u] = timer++;
    up[u][0] = p;
    for (int i = 1; i < MAXLOG; i++) {
        up[u][i] = up[up[u][i-1]][i-1];
    }
    dist_root[u] = d;

    for (auto [v, w] : G[u]) {
        if (v == p) continue;
        dfs(v, u, d+w);
    }

    tout[u] = timer++;
}

bool is_ancestor(int u, int v) {
    return tin[u] <= tin[v] && tout[u] >= tout[v];
}

int lca(int u, int v) {
    if (is_ancestor(u, v)) return u;
    if (is_ancestor(v, u)) return v;

    rev(i, MAXLOG-1, 0) {
        if (!is_ancestor(up[u][i], v)) u = up[u][i];
    }
    return up[u][0];
}

ll dist(int u, int v) {
    int c = lca(u, v);
    return dist_root[u] + dist_root[v] - 2 * dist_root[c];
}

int max_score(int N, int x, int y, ll k, vi U,vi V,vi W) {
    n = N, m = sz(U);
    G.assign(n, vector<pi>()); rep(i, 0, m) G[U[i]].push_back({V[i], W[i]}), G[V[i]].push_back({U[i], W[i]});
    up.assign(n, vi(MAXLOG));
    vi state(n);

    dfs(0,0,0);
    priority_queue<pi, vector<pi>, greater<pi>> pq;
    rep(i, 0, n) pq.push({min(dist(x,i), dist(y,i)), i});

    while (!pq.empty()) {
        auto [w,u] = pq.top(); pq.pop();
        if (w>k) break;

        if (state[u] == 0) {
            state[u] = 1;
            pq.push({max(dist(x,u),dist(y,u)), u});
            k -= w;
        } else {
            state[u] = 2;
            k -= w;
        }
    }

    int ans = accumulate(all(state), 0);
    return ans;
}
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