Submission #500415

#	Time	Username	Problem	Language	Result	Execution time	Memory
500415		zhougz	Village (BOI20_village)	C++17	100 / 100	110 ms	28032 KiB

Village

#include <bits/stdc++.h>

using namespace std;

#define int long long

int n;
const int MAXN = 100'050;
vector<vector<int>> v(MAXN, vector<int>());

pair<int, vector<int>> slv1(int n, vector<vector<int>> v) {
	int res = 0;
	vector<int> arr(n); // arr[i] denotes guy at place where i was
	iota(arr.begin(), arr.end(), 0);
	function<void(int, int)> dfs = [&](int x, int p) -> void {
		for (auto z : v[x]) {
			if (z != p) {
				dfs(z, x);
			}
		}
		if (arr[x] == x) {
			if (x != 0) {
				swap(arr[x], arr[p]);
			} else {
				swap(arr[0], arr[v[0][0]]);
			}
			res += 2;
		}
	};
	dfs(0, -1);
	vector<int> ans(n);
	for (int i = 0; i < n; i++) {
		ans[arr[i]] = i;
	}
	return make_pair(res, ans);
}

pair<int, vector<int>> slv2(int n, vector<vector<int>> v) {
	int mx = 0, cnt = 0, centroid = -1;
	vector<int> sz(n), pre(n);
	function<void(int, int)> dfs = [&](int x, int p) -> void {
		pre[cnt++] = x;
		sz[x] = 1;
		for (auto z : v[x]) {
			if (z != p) {
				dfs(z, x);
				sz[x] += sz[z];
				mx += min(sz[z], n - sz[z]);
			}
		}
		if (sz[x] > n / 2 && centroid == -1) {
			centroid = x;
		}
	};
	dfs(0, -1);
	vector<int> ans(n);
	for (int i = 0; i < n; i++) {
		ans[pre[i]] = pre[(i + n / 2) % n];
	}
	return make_pair(2 * mx, ans);
}

int32_t main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	cin >> n;
	for (int i = 0, a, b; i < n - 1; i++) {
		cin >> a >> b;
		a--;
		b--;
		v[a].push_back(b);
		v[b].push_back(a);
	}
	int res1, res2;
	vector<int> arr1, arr2;
	tie(res1, arr1) = slv1(n, v);
	tie(res2, arr2) = slv2(n, v);
	cout << res1 << ' ' << res2 << '\n';
	for (auto x : arr1) {
		cout << x + 1 << ' ';
	}
	cout << '\n';
	for (auto x : arr2) {
		cout << x + 1 << ' ';
	}
	cout << '\n';
	return 0;
}

• Subtask 1: 12 / 12
• Subtask 2: 38 / 38
• Subtask 3: 50 / 50