Submission #293621

#	Time	Username	Problem	Language	Result	Execution time	Memory
293621		errorgorn	Power Plant (JOI20_power)	C++14	100 / 100	1252 ms	75576 KiB

power

//雪花飄飄北風嘯嘯
//天地一片蒼茫

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
#define ll long long
#define ii pair<ll,ll>
#define iii pair<ii,ll>
#define fi first
#define se second
#define endl '\n'
#define debug(x) cout << #x << " is " << x << endl

#define rep(x,start,end) for(auto x=(start)-((start)>(end));x!=(end)-((start)>(end));((start)<(end)?x++:x--))
#define all(x) (x).begin(),(x).end()
#define sz(x) (int)(x).size()

#define indexed_set tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>
//change less to less_equal for non distinct pbds, but erase will bug

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

int n;
vector<int> al[200005];
string s;

map<ii,int> memo;

int par[200005];
int val[200005];

int dfs(int i,int p){
	if (memo.count(ii(i,p))) return memo[ii(i,p)];
	int res=0;
	
	if (par[i]==-2){
		for (auto &it:al[i]){
			if (it==p) continue;
			res+=dfs(it,i);
		}
		
		par[i]=p;
		val[i]=res;
	}
	else{
		res=val[i];
		if (par[i]!=-1) res+=dfs(par[i],i);
		if (p!=-1) res-=dfs(p,i);
	}
	
	res+=(s[i]=='1'?-1:0);
	return memo[ii(i,p)]=max(res,(s[i]=='1'?1:0));
}

int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin.exceptions(ios::badbit | ios::failbit);
	
	cin>>n;
	rep(x,0,n) par[x]=-2;
	
	int a,b;
	rep(x,1,n){
		cin>>a>>b;
		a--,b--;
		
		al[a].push_back(b);
		al[b].push_back(a);
	}
	
	cin>>s;
	
	int ans=0;
	rep(x,0,n) if (s[x]=='1') ans++;
	ans=min(ans,2);
	
	rep(x,0,n){
		ans=max(dfs(x,-1),ans);
	}
	
	cout<<ans<<endl;
}

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