Submission #542130

#	Time	Username	Problem	Language	Result	Execution time	Memory
542130		blue	Power Plant (JOI20_power)	C++17	0 / 100	6 ms	9724 KiB

power

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;

using vi = vector<int>;
using vvi = vector<vi>;

const int mx = 200'000;

int N;
vi edge[1+mx];

int DP[1+mx][3];
vi power;
vi children[1+mx];

int res = 1;

void dfs(int u, int p)
{
	for(int v : edge[u])
	{
		if(v == p) continue;
		children[u].push_back(v);
		dfs(v, u);
	}

	if(power[u]) DP[u][0] = 1;
	else DP[u][0] = 0;


	if(power[u]) DP[u][1] = -1;
	else DP[u][1] = 0;
	for(int v : children[u])
		DP[u][1] += max({DP[v][0], DP[v][1], 0});

	int curr;
	if(power[u]) curr = 1;
	else curr = 0;

	int currres = -1'000'000'000;
	for(int v : children[u])
		currres = max(currres, curr + DP[v][1]);

	res = max(res, currres);

	if(power[u]) curr = -1;
	else curr = 1;
	for(int v : children[u])
		curr += max(0, DP[v][1]);

	res = max(res, curr);
}

int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);

	cin >> N;
	for(int e = 1; e <= N-1; e++)
	{
		int a, b;
		cin >> a >> b;
		edge[a].push_back(b);
		edge[b].push_back(a);
	}

	power = vi(1+N);
	for(int i = 1; i <= N; i++)
	{
		char c;
		cin >> c;
		if(c == '1') power[i] = 1;
		else power[i] = 0;
	}

	dfs(1, 0);

	cout << res << '\n';
}

• Subtask 1: 0 / 6
• Subtask 2: 0 / 41
• Subtask 3: 0 / 53