Submission #529048

#	Time	Username	Problem	Language	Result	Execution time	Memory
529048		d2k05	Power Plant (JOI20_power)	C++14	0 / 100	12 ms	23808 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 cnt = 0, h = 0;
	for (auto to : adj[v])
		cnt += d[to], h += b[to];
	ans = max(ans, (int)a[v - 1]);
	ans = max(ans, cnt + (h > 0 ? -a[v - 1] : a[v - 1]));
	for (auto to : adj[v]) {
		if (to != p) {
			int dv = d[v], dto = d[to];
			int bv = b[v], bto = b[to];
			d[v] -= d[to];
			if (d[v] <= 1) {
				if (a[v - 1])
					d[v] = b[v] = 1;
				else {
					if (d[v] <= 0)
						b[v] = 0;
				}
			}
			if (d[to] == 1 && a[to - 1] == 1) 
				d[to] = b[to] = 0;
			d[to] += d[v]; b[to] |= b[v];
			d[to] += a[to - 1] * (b[to] > 0 ? -1 : 1);
			b[to] |= a[to - 1];
			if (!d[to])
				d[to] = b[to] = a[to - 1];
			dfs(to, v);
			d[v] = dv, d[to] = dto, b[v] = bv, b[to] = bto;
		}
	}
}

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';
	for (int i = 1; i <= n; ++i) {
		for (int j = 1; j <= n; ++j) d[j] = b[j] = 0;
		calc(i);
		ans = max(ans, d[i]);
	}
	cout << ans;
	return 0;
}

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