Submission #1221944

#	Time	Username	Problem	Language	Result	Execution time	Memory
1221944		mingga	Power Plant (JOI20_power)	C++20	100 / 100	70 ms	26692 KiB

power

#include "bits/stdc++.h"

using namespace std;

#define ln "\n"
#define pb push_back
#define fi first
#define se second
#define all(x) (x).begin(), (x).end()
#define sz(x) ((int)(x).size())
#define int long long
const int mod = 1e9 + 7;
const int inf = 2e18;
const int N = 2e5 + 7;
int n;
vector<int> g[N];
bool a[N];
int dp[N], ans;


void dfs(int u, int p) {
	int mx = 0;
	for(int v : g[u]) {
		if(v == p) continue;
		dfs(v, u);
		dp[u] += dp[v];
		mx = max(mx, dp[v]);
	}
	if(a[u]) dp[u] = max(dp[u] - 1, 1ll);
	ans = max({ans, dp[u], mx + a[u]});
}

signed main() {
	cin.tie(0) -> sync_with_stdio(0);
	#define task ""
	if(fopen(task ".INP", "r")) {
		freopen(task ".INP", "r", stdin);
		freopen(task ".OUT", "w", stdout);
	}
	cin >> n;
	for(int i = 1; i < n; i++) {
		int u, v; cin >> u >> v;
		g[u].pb(v);
		g[v].pb(u);
	}
	for(int i = 1; i <= n; i++) {
		char c; cin >> c;
		if(c == '1') a[i] = 1;
	}
	dfs(1, 0);
	cout << ans << ln;
    cerr << "\nTime: " << clock() * 1000 / CLOCKS_PER_SEC;
}

Compilation message (stderr)

power.cpp: In function 'int main()':
power.cpp:37:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   37 |                 freopen(task ".INP", "r", stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
power.cpp:38:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   38 |                 freopen(task ".OUT", "w", stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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