Submission #870177

#	Time	Username	Problem	Language	Result	Execution time	Memory
870177		vjudge1	Ball Machine (BOI13_ballmachine)	C++17	100 / 100	142 ms	23764 KiB

ballmachine

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

const int N = 1e5 + 15, L = 2e0 + 20;
int n, q, r, par[N][L], lst[N], st[N], ft[N], dfa[N], num[N];
bool ext[4 * N], mark[N];
vector<int> adj[N];

bool cmp(const int &a, const int &b) {
	return lst[a] < lst[b];
}

void dfs1(int v, int p) {
	lst[v] = v;
	for (int u: adj[v]) {
		dfs1(u, v);
		lst[v] = min(lst[v], lst[u]);
	}
}

void dfs2(int v, int p) {
	static int time = 0;
	dfa[time] = v;
	st[v] = time++;
	for (int u: adj[v])
		if (u != p)
			dfs2(u, v);
	ft[v] = time;
}

void make_tree(int l, int r, int t) {
	if (r - l == 1) {
		ext[t] = (st[dfa[l]] == ft[dfa[l]] - 1);
		return;
	}

	int k = (r + l + 1) / 2;
	make_tree(l, k, 2 * t);
	make_tree(k, r, 2 * t + 1);
	ext[t] = (ext[2 * t] | ext[2 * t + 1]);
}

int find_place(int l, int r, int t) {
	if (r - l == 1) 
		return dfa[l];

	int k = (r + l + 1) / 2;
	if (ext[2 * t])
		return find_place(l, k, 2 * t);
	else
		return find_place(k, r, 2 * t + 1);
}

void update(int p, bool x, int l, int r, int t) {
	if (r - l == 1) {
		ext[t] = x;
		return;
	}

	int k = (r + l + 1) / 2;
	if (p < k)
		update(p, x, l, k, 2 * t);
	else
		update(p, x, k, r, 2 * t + 1);
	ext[t] = (ext[2 * t] | ext[2 * t + 1]);
}

void read_input() {
	cin >> n >> q;
	for (int i = 1; i <= n; i++) {
		cin >> par[i][0];
		if (par[i][0] != 0)
			adj[par[i][0]].push_back(i);
		else
			r = i;
	}
}

void solve() {
	memset(lst, 63, sizeof lst);
	dfs1(r, 0);
	for (int i = 1; i <= n; i++) 
		sort(adj[i].begin(), adj[i].end(), cmp);
	dfs2(r, 0);
	make_tree(0, n, 1);
	for (int i = 1; i < L; i++)
		for (int j = 1; j <= n; j++)
			par[j][i] = par[par[j][i - 1]][i - 1];

	while (q--) {
		int t;
		cin >> t;
		if (t == 1) {
			int k;
			cin >> k;
			for (int i = 0; i < k; i++) {
				int v = find_place(0, n, 1);
				update(st[v], false, 0, n, 1);
				mark[v] = true;
				num[par[v][0]]++;
				if (num[par[v][0]] == adj[par[v][0]].size()) 
					update(st[par[v][0]], true, 0, n, 1);
				if (i == k - 1)
					cout << v << '\n';
			}
		}
		else {
			int x;
			cin >> x;

			int p = x, res = 0;
			for (int i = L - 1; i >= 0; i--)
				if (mark[par[p][i]]) {
					p = par[p][i];
					res += (1 << i);
				}
			cout << res << '\n';
			
			mark[p] = false;
			num[par[p][0]]--;
			if (num[p] == adj[p].size()) {
				update(st[p], true, 0, n, 1);
				update(st[par[p][0]], false, 0, n, 1);
			}
		}
	}
}

int main() {
	ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	read_input(), solve();
	return cout << '\n', 0;
}

Compilation message (stderr)

ballmachine.cpp: In function 'void solve()':
ballmachine.cpp:101:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  101 |     if (num[par[v][0]] == adj[par[v][0]].size())
      |         ~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
ballmachine.cpp:121:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  121 |    if (num[p] == adj[p].size()) {
      |        ~~~~~~~^~~~~~~~~~~~~~~~

• Subtask 1: 25 / 25
• Subtask 2: 30 / 30
• Subtask 3: 40 / 40
• Subtask 4: 5 / 5