Submission #848821

#	Time	Username	Problem	Language	Result	Execution time	Memory
848821		qthang2k11	Cats or Dogs (JOI18_catdog)	C++17	100 / 100	335 ms	27732 KiB

catdog

#include "catdog.h"
#include <bits/stdc++.h>
using namespace std;
 
const int N = 1e5 + 5;
 
vector<int> adj[N];
 
int par[N], chain[N], head[N], tail[N], tin[N], sz[N];
int tchain = 0, tcur = 0, n;
 
void dfs_size(int x, int p) {
	sz[x] = 1;
	par[x] = p;
	for (int y: adj[x]) {
		if (y == p) continue;
		dfs_size(y, x);
		sz[x] += sz[y];
	}
}
 
void dfs(int x) {
	tin[x] = ++tcur;	
	if (!chain[x]) {
		chain[x] = ++tchain;
		head[tchain] = x;
	}
	tail[chain[x]] = x;
	int spec = -1;
	for (int y: adj[x]) {
		if (y == par[x]) continue;
		if (spec == -1 || sz[y] > sz[spec])
			spec = y;
	}
	if (spec != -1) {
		chain[spec] = tchain;
		dfs(spec);
	}
	for (int y: adj[x])
		if (y != par[x] && y != spec)
			dfs(y);
}
 
const int INF = 1e9;
struct Node {
	int val[2][2];
	
	Node() = default;
	
	Node(bool set_inf) {
		if (set_inf) {
			for (int a: {0, 1})
				for (int b: {0, 1})
					val[a][b] = INF;
		}
	}
	
	int res() const {
		int ans = INF;
		for (int a: {0, 1})
			for (int b: {0, 1})
				ans = min(ans, val[a][b]);
		return ans;
	}
	
	Node operator + (const Node &other) const {
		Node ans;
		for (int a = 0; a < 2; a++) {
			for (int d = 0; d < 2; d++) {
				int cur = INF;
				for (int b = 0; b < 2; b++)
					for (int c = 0; c < 2; c++)
						cur = min(cur, val[a][b] + other.val[c][d] + (b != c));
				ans.val[a][d] = cur;
			}
		}
		return ans;
	}
} IT[N << 2];
 
int dp[N][2]; // only consider vertices NOT in heavy chain, segment tree will consider the rest + dp
int up_par[N][2]; // for chain_head to update dp[par]'s values
 
Node node_inf(true);
 
void build(int id, int l, int r) {
	if (l == r) {
		for (int a: {0, 1})
			for (int b: {0, 1})
				IT[id].val[a][b] = (a != b ? INF : 0);
		return;
	}
	int mid = (l + r) / 2;
	build(id << 1, l, mid);
	build(id << 1 | 1, mid + 1, r);
	IT[id] = IT[id << 1] + IT[id << 1 | 1];
}
 
void initialize(int n, vector<int> A, vector<int> B) {
	::n = n;
	for (int i = 0; i < n - 1; i++) {
		int x = A[i], y = B[i];
		adj[x].emplace_back(y);
		adj[y].emplace_back(x);
	}
	dfs_size(1, 0);
	dfs(1);
	build(1, 1, n);
}
 
void invalid_color(int x, int c, int id, int l, int r) {
	if (l == r) {
		// if (c ^ color) == 0 => skip
		IT[id] = node_inf;
		for (int col: {0, 1})
			if ((col + 1) ^ c)
				IT[id].val[col][col] = dp[x][col];
		return;
	}
	int mid = (l + r) / 2;
	if (x <= mid) invalid_color(x, c, id << 1, l, mid);
	else invalid_color(x, c, id << 1 | 1, mid + 1, r);
	IT[id] = IT[id << 1] + IT[id << 1 | 1];
}
 
void update_val(int x, int w[], int id, int l, int r) {
	if (l == r) {
		for (int c: {0, 1})
			if (IT[id].val[c][c] != INF)
				IT[id].val[c][c] += w[c];
		return;
	}
	int mid = (l + r) / 2;
	if (x <= mid) update_val(x, w, id << 1, l, mid);
	else update_val(x, w, id << 1 | 1, mid + 1, r);
	IT[id] = IT[id << 1] + IT[id << 1 | 1];
}
 
Node get_range(int x, int y, int id, int l, int r) {
	if (x <= l && r <= y) return IT[id];
	int mid = (l + r) / 2;
	if (y <= mid) return get_range(x, y, id << 1, l, mid);
	if (x > mid) return get_range(x, y, id << 1 | 1, mid + 1, r);
	return get_range(x, y, id << 1, l, mid) + get_range(x, y, id << 1 | 1, mid + 1, r);
}
 
int get(int x) {
	int xchain = chain[x], head_ = head[xchain], tail_ = tail[xchain];
	while (xchain != 1) {
		auto S = get_range(tin[head_], tin[tail_], 1, 1, n);
		int val[] = {min(S.val[0][0], S.val[0][1]), min(S.val[1][0], S.val[1][1])};
		int upd[] = {-up_par[tin[head_]][0] + min(val[0], val[1] + 1), 
								 -up_par[tin[head_]][1] + min(val[0] + 1, val[1])};
		update_val(tin[par[head_]], upd, 1, 1, n);
		dp[tin[par[head_]]][0] += upd[0];
		dp[tin[par[head_]]][1] += upd[1];
		up_par[tin[head_]][0] = min(val[0], val[1] + 1);
		up_par[tin[head_]][1] = min(val[0] + 1, val[1]);
		xchain = chain[par[head_]];
		tail_ = tail[xchain];
		head_ = head[xchain];
	}
	return get_range(tin[head_], tin[tail_], 1, 1, n).res();
}
 
int solve(int s, int c) {
	invalid_color(tin[s], c, 1, 1, n);
	return get(s);
}
 
int cat(int v) {
  return solve(v, 2);
}
 
int dog(int v) {
  return solve(v, 1);
}
 
int neighbor(int v) {
  return solve(v, 0);
}

• Subtask 1: 8 / 8
• Subtask 2: 30 / 30
• Subtask 3: 62 / 62