Submission #1342268

#TimeUsernameProblemLanguageResultExecution timeMemory
1342268madamadam3Toy Train (IOI17_train)C++20
0 / 100
5 ms2116 KiB
#include "train.h"
#include <bits/stdc++.h>
using namespace std;
using pi = pair<int, int>;
using vi = vector<int>;
using vvi = vector<vi>;
#define bg(x) (x).begin()
#define en(x) (x).end()
#define all(x) bg(x), en(x)
#define sz(x) (int((x).size()))

int n, m;
vi charging, owner, scc;
vvi G, R;

// node, which owner, allowing charging stations
void dfs1(int u, int o, int t, vi &order, vi &cmp) {
	for (auto v : G[u]) {
		if (cmp[v] != -1) continue;
		if (owner[v] != o) continue;
		if (charging[v] && !t) continue;

		cmp[v] = cmp[u];
		dfs1(v, o, t, order, cmp);
	}
	order.push_back(u);
}

vi who_wins(vi a, vi r, vi u, vi v) {
	n = sz(a), m = sz(u);
	charging = r; owner = a; scc.assign(n, -1);
	G.assign(n, vi()); R.assign(n, vi()); for (int i = 0; i < m; i++) G[u[i]].push_back(v[i]), R[v[i]].push_back(u[i]);

	int timer = 0;
	vi cmp1(n, -1), order1, order2; 
	for (int i = 0; i < n; i++) {
		if (cmp1[i] != -1 || owner[i] != 1) continue;
		cmp1[i] = timer++; dfs1(i, 1, 1, order1, cmp1);
	}

	timer = 0;
	reverse(all(order1));
	for (auto i : order1) {
		if (scc[i] != -1) continue;
		scc[i] = timer++; dfs1(i, 1, 1, order2, scc);
	}

	vi has_charger(n, 0);
	vvi S(n, vi()), B(n, vi()); vi deg(n, 0), len(n, 0);
	set<pi> seen;
	for (int i = 0; i < n; i++) {
		if (scc[i] == -1) continue;
		has_charger[scc[i]] |= 1;
		len[scc[i]]++;
		for (auto v : G[i]) {
			if (scc[i] == scc[v]) continue;
			if (scc[v] == -1) continue;
			if (seen.count({scc[i], scc[v]})) continue;
			seen.insert({scc[i], scc[v]});
			S[scc[i]].push_back(scc[v]);
			B[scc[v]].push_back(scc[i]);
			deg[scc[v]]++;
		}
	}

	for (int i = 0; i < n; i++) if (has_charger[i] && len[i] <= 1) has_charger[i] = 0;
	queue<int> q; for (int i = 0; i < n; i++) if (deg[i] == 0 && len[i] > 0) q.push(i);
	vector<int> order;
	while (!q.empty()) {
		int u = q.front(); q.pop();
		order.push_back(u);
		for (auto v : S[u]) {
			if (--deg[v] == 0) q.push(v);
		}
	}

	reverse(all(order));
	for (auto u : order) {
		for (auto v : S[u]) {
			has_charger[u] |= has_charger[v];
		}
	}

	vi res(n, 0);
	for (int i = 0; i < n; i++) if (scc[i] != -1 && has_charger[scc[i]]) res[i] = 1;
	return res;
}
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