Submission #598195

#	Time	Username	Problem	Language	Result	Execution time	Memory
598195		Bobaa	Meetings 2 (JOI21_meetings2)	C++17	Compilation error	0 ms	0 KiB

meetings2

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

const int maxn = 2e5 + 5; 
const int logn = log2(maxn) + 1; 

vector<int> adj[maxn]; 
int par[logn][maxn], sz[maxn], dep[maxn], c[maxn]; 

void dfs1(int curnode, int prvnode, int d = 1) {
	par[0][curnode] = prvnode; 
	for (int i = 1; i < logn; i++) par[i][curnode] = par[i - 1][par[i - 1][curnode]]; 
	sz[curnode] = 1; 
	dep[curnode] = d; 
	for (auto v : adj[curnode]) if (v != prvnode) {
		dfs1(v, curnode, d + 1); 
		sz[curnode] += sz[v]; 
	}
}

int dfs2(int curnode, int prvnode) {
	for (auto v : adj[curnode]) if (v != prvnode && sz[v] > sz[0] / 2) return dfs2(v, curnode); 
	return curnode; 
}

int lca(int a, int b) {
	if (dep[a] > dep[b]) swap(a, b); 
	for (int i = logn - 1; i >= 0; i--)  if (dep[a] <= dep[b] - (1 << x)) b = par[i][b]; 
	if (a == b) return a; 
	for (int i = logn - 1; i >= 0; i--)  if (par[i][a] != par[i][b]) {
		a = par[i][a]; 
		b = par[i][b]; 
	}
	return par[0][a]; 
}

int main() {
	ios_base::sync_with_stdio(false); 
	cin.tie(nullptr); 
	int n; 
	cin >> n; 
	for (int i = 0, a, b; i < n - 1; i++) {
		cin >> a >> b; 
		a--; 
		b--; 
		adj[a].push_back(b); 
		adj[b].push_back(a); 
	}
	dfs1(0, 0); 
	int cen = dfs2(0, 0); 
	int l = cen, r = cen; 
	vector<pair<int, int>> vec; 
	for (int i = 0; i < n; i++) vec.push_back({sz[i], i}); 
	sort(vec.rbegin(), vec.rend()); 
	int ans[n + 1], cur = 1; 
	fill(ans, ans + n + 1, 0); 
	for (int i = 0; i < n; i++) {
		int idx = vec[i].second; 
		int d1 = dep[l] + dep[idx] - 2 * dep[lca(l, idx)] + 1; 
		int d2 = dep[r] + dep[idx] - 2 * dep[lca(r, idx)] + 1; 
		if (d1 < d2) {
			swap(d1, d2); 
			swap(l, r); 
		}
		if (d1 > cur) {
			cur = d1; 
			r = idx; 
		}
		ans[vec[i].first] = cur; 
	}
	for (int i = n - 1; i >= 0; i--) ans[i] = max(ans[i], ans[i + 1]); 
	for (int i = 1; i <= n; i++) {
		if (i & 1) cout << "1" << '\n'; 
		else cout << ans[i >> 1] << '\n'; 
	}
	return 0; 
}

Compilation message (stderr)

meetings2.cpp: In function 'int lca(int, int)':
meetings2.cpp:28:68: error: 'x' was not declared in this scope
   28 |  for (int i = logn - 1; i >= 0; i--)  if (dep[a] <= dep[b] - (1 << x)) b = par[i][b];
      |                                                                    ^