Submission #438707

#	Time	Username	Problem	Language	Result	Execution time	Memory
438707		soroush	Power Plant (JOI20_power)	C++17	0 / 100	3 ms	4992 KiB

power

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<int , int> pii;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int maxn = 2e5 + 10;
const ll mod = 1e9+7;

#define pb push_back
#define endl '\n'
#define dokme(x) cout << x , exit(0)
#define ms(x , y) memset(x , y , sizeof x)
ll pw(ll a, ll b, ll md = mod){ll res = 1;while(b){if(b&1){res=(a*res)%md;}a=(a*a)%md;b>>=1;}return(res);}

int n;
string s;
vector < int > adj[maxn];
/*
int dfs(int v , int par){
	int res = 0;
	for(int u : adj[v])if(u ^ par)
		res += dfs(u , v);
	if(s[v] == '1')
		res = max(res - 1 , 1);
	return res;
}

int solve(int v){
	int res = 0;
	for(auto u : adj[v])
		res = max(res , dfs(u , v));
	return res + 1;
}
*/

int sz[maxn];
bool hide[maxn];

void plant(int v){
	sz[v] = 1, hide[v] = 1;
	for(auto u : adj[v])if(!hide[u])
		plant(u), sz[v] += sz[u];
	hide[v] = 0;
}

int cen(int v , int n , int par = 0 , bool found = 0){
	while(!found){
		found = 1;
		for(auto u : adj[v])if(!hide[u] and u^par and sz[u] * 2 > n){
			found = 0 , par = v , v = u;
			break;
		}
	}
	return v;
}

int dfs(int v){
	int res = 0;
	hide[v] = 1;
	for(int u : adj[v])if(!hide[u])
		res += dfs(u);
	hide[v] = 0;
	if(s[v] == '1')
		res = max(res - 1 , 1);
	return res;
}

int Solve(int v){
	hide[v] = 1;
	int ans = 0;
	if(s[v] == '1'){
		int mx = 0 , sum = 0;
		for(int u : adj[v])if(!hide[u]){
			int res = dfs(u);
			mx = max(mx , res);
			sum += max(res , 0);
		}
		ans = max(ans, mx + 1);
		ans = max(ans, sum - 1);
	}
	else{
		for(int u : adj[v])if(!hide[u])
			ans += max(0 , dfs(u));
	}
	return ans;
}

int solve(int v = 1){
	plant(v);
	v = cen(v , sz[v]);
	int ans = Solve(v);
	for(auto u : adj[v])if(!hide[u])
		ans = max(ans, solve(u));
	return ans;
}

int32_t main(){
	ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
	cin >> n;
	for(int i = 1 ; i < n ; i ++){
		int u , v;
		cin >> u >> v;
		u -- , v --;
		adj[u].pb(v);
		adj[v].pb(u);
	}
	cin >> s;
	cout << max(0 , solve());
	return(0);
}

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