Submission #1256412

#	Time	Username	Problem	Language	Result	Execution time	Memory
1256412		mingga	Synchronization (JOI13_synchronization)	C++20	100 / 100	212 ms	23636 KiB

synchronization

// Author: caption_mingle
#include "bits/stdc++.h"

using namespace std;

#define ln "\n"
#define pb push_back
#define fi first
#define se second
#define all(x) (x).begin(), (x).end()
#define sz(x) ((int)(x).size())
#define ll long long
const int mod = 1e9 + 7;
const int inf = 2e9;
const int N = 1e5 + 7;
int n, m, q, in[N], out[N], timer, ans[N], lst[N], par[N], up[N][20];
bool active[N];
pair<int, int> e[N];

vector<int> g[N];

void dfs(int u, int p) {
	in[u] = ++timer;
	for(int i = 1; i < 20; i++) up[u][i] = up[up[u][i - 1]][i - 1];
	for(int v : g[u]) {
		if(v == p) continue;
		par[v] = u;
		up[v][0] = u;
		dfs(v, u);
	}
	out[u] = timer;
}

struct BIT {
	int n;
	vector<int> bit;
	BIT() {}
	BIT(int n) : n(n) {
		bit.resize(n + 1, 0);
	}
	void update(int u, int x) {
		for(; u <= n; u += (u & -u)) bit[u] += x;
	}
	int get(int u) {
		int ans = 0;
		for(; u > 0; u -= (u & -u)) ans += bit[u];
		return ans;
	}
	void update(int l, int r, int x) {
		update(l, x);
		update(r + 1, -x);
	}
} bit;

int find(int u) {
	for(int i = 19; i >= 0; i--) {
		if(bit.get(in[up[u][i]]) == bit.get(in[u])) {
			u = up[u][i];
		}
	}
	return u;
}

signed main() {
	cin.tie(0) -> sync_with_stdio(0);
	#define task ""
	if(fopen(task ".INP", "r")) {
		freopen(task ".INP", "r", stdin);
		freopen(task ".OUT", "w", stdout);
	}
	cin >> n >> m >> q;
	for(int i = 1; i < n; i++) {
		int u, v; cin >> u >> v;
		g[u].pb(v);
		g[v].pb(u);
		e[i] = {u, v};
	}
	bit = BIT(n);
	dfs(1, 0);
	for(int i = 1; i <= n; i++) {
		bit.update(in[i], out[i], 1);
		ans[i] = 1;
	}
	while(m--) {
		int id; cin >> id;
		auto [u, v] = e[id];
		if(par[v] != u) swap(u, v);
		if(!active[id]) {
			ans[find(u)] += ans[v] - lst[v];
			bit.update(in[v], out[v], -1);
			active[id] = 1;
		} else {
			ans[v] = lst[v] = ans[find(u)];
			bit.update(in[v], out[v], 1);
			active[id] = 0;
		}
	}
	while(q--) {
		int x; cin >> x;
		cout << ans[find(x)] << ln;
	}
    cerr << "\nTime: " << clock() * 1000 / CLOCKS_PER_SEC;
}

Compilation message (stderr)

synchronization.cpp: In function 'int main()':
synchronization.cpp:68:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   68 |                 freopen(task ".INP", "r", stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
synchronization.cpp:69:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   69 |                 freopen(task ".OUT", "w", stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 20 / 20
• Subtask 3: 10 / 10
• Subtask 4: 20 / 20
• Subtask 5: 40 / 40