Submission #529053

#	Time	Username	Problem	Language	Result	Execution time	Memory
529053		d2k05	Power Plant (JOI20_power)	C++14	100 / 100	188 ms	50412 KiB

power

#include <bits/stdc++.h>

#define fastio ios_base :: sync_with_stdio(0), cin.tie(0);

using namespace std;
using ll = long long;

const int mxN = 1e6 + 5, mod = 1e9 + 7;

int n, d[mxN], b[mxN], ans; string a;
vector <int> adj[mxN];

void calc(int v, int p = -1) {
	for (auto to : adj[v]) {
		if (to != p) {
			calc(to, v);
			d[v] += d[to];
		}
	}
	if (d[v] > 0) 
		d[v] -= a[v - 1];
	if (!d[v]) 
		d[v] = a[v - 1];
}

void dfs(int v, int p = -1) {
	int ret = 0, cnt = 0;
	for (auto to : adj[v]) {
		if (d[to] > 0)
			++cnt;
		ret += d[to];
	}
	if (cnt <= 1) ret += a[v - 1]; 
	else {
		if (ret > 0) ret -= a[v - 1];
		if (!ret) ret = a[v - 1];
	}
	ans = max(ans, ret);
	for (auto to : adj[v]) {
		if (to != p) {
			int dv = d[v], dto = d[to];
			d[v] -= d[to];
			if (d[v] <= 1) {
				if (a[v - 1])
					d[v] = 1;
			}
			if (d[to] == 1 && a[to - 1] == 1) d[to] = 0;
			d[to] += d[v];
			if (d[to] > 0) d[to] -= a[to - 1];
			if (!d[to]) d[to] = a[to - 1];
			dfs(to, v);
			d[v] = dv, d[to] = dto;
		}
	}
}

int main() {
	fastio;
	cin >> n;
	for (int i = 1, u, v; i < n; ++i) {
		cin >> u >> v;
		adj[u].push_back(v);
		adj[v].push_back(u);
	}
	cin >> a;
	for (auto &x : a) x -= '0';
	calc(1); dfs(1);
	cout << ans;
	return 0;
}

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