Submission #829069

#	Time	Username	Problem	Language	Result	Execution time	Memory
829069		PurpleCrayon	Split the Attractions (IOI19_split)	C++17	0 / 100	6 ms	10392 KiB

split

#include "split.h"
#include <bits/stdc++.h>
using namespace std;

#define sz(v) int(v.size())
#define ar array
typedef long long ll;
const int N = 2e5+10, MOD = 1e9+7;

struct DSU {
	vector<int> par, sz;
	DSU() {}
	DSU(int n): par(n) {
		iota(par.begin(), par.end(), 0);
		sz.assign(n, 1);
	}

	int find_set(int v) {
		return v == par[v] ? v : par[v] = find_set(par[v]);
	}

	bool union_sets(int a, int b) {
		if ((a = find_set(a)) == (b = find_set(b))) return false;
		if (sz[a] < sz[b]) swap(a, b);
		par[b] = a, sz[a] += sz[b], sz[b] = 0;
		return true;
	}
} d;

int n, m, sub[N], par[N];
vector<int> adj[N];

int dfs_sub(int c, int p) {
	sub[c] = 1, par[c] = p;
	for (int nxt : adj[c]) if (nxt != p) {
		sub[c] += dfs_sub(nxt, c);
	}
	return sub[c];
}

bool vis[N];
vector<int> gather(int root, int p, int cnt) {
	memset(vis, 0, sizeof(vis)); 

	vector<int> q{root}; vis[root] = vis[p] = 1;
	for (int rep = 0; rep < sz(q) && sz(q) <= cnt; rep++) {
		int c = q[rep];
		for (int nxt : adj[c]) if (!vis[nxt]) {
			q.push_back(nxt);
			vis[nxt] = 1;
		}
	}

	assert(sz(q) >= cnt);
	q.resize(cnt);
	assert(sz(q) == cnt);
	return q;
}

vector<int> find_split(int _n, int p1, int p2, int p3, vector<int> p, vector<int> q) {
	n = _n, m = sz(p);
	assert(m == n-1);
	for (int i = 0; i < m; i++) {
		int x = p[i], y = q[i];
		adj[x].push_back(y), adj[y].push_back(x);
	}

	vector<pair<int, int>> cols(3);
	cols[0] = {p1, 1}, cols[1] = {p2, 2}, cols[2] = {p3, 3};
	sort(cols.begin(), cols.end());

	dfs_sub(0, -1);

	pair<int, int> cut{-1, -1};
	for (int c = 0; c < n; c++) {
		if (sub[c] >= cols[0].first && n - sub[c] >= cols[1].second) {
			cut = {c, par[c]};
		}

		if (n - sub[c] >= cols[0].first && sub[c] >= cols[1].second) {
			cut = {par[c], c};
		}
	}

	if (cut == make_pair(-1, -1)) return vector<int>(n, 0);
	vector<int> one = gather(cut.first, cut.second, cols[0].first);
	vector<int> two = gather(cut.second, cut.first, cols[1].first);
	// cout << sz(one) << ' ' << sz(two) << endl;
	vector<int> ans(n, cols[2].second);
	for (int x : one) ans[x] = cols[0].second;
	for (int x : two) ans[x] = cols[1].second;
	return ans;
}

• Subtask 1: 0 / 7
• Subtask 2: 0 / 11
• Subtask 3: 0 / 22
• Subtask 4: 0 / 24
• Subtask 5: 0 / 36