Submission #438382

#	Time	Username	Problem	Language	Result	Execution time	Memory
438382		bobbilyking	Friend (IOI14_friend)	C++17	46 / 100	33 ms	5064 KiB

friend

#include "friend.h"
#include<bits/stdc++.h>
using namespace std;

#define N 100010
typedef long long int ll;
ll cost[N];
vector<ll> adj[N];
int dp[N];
int lefts,rights;
void match(int i,  int p ,int v){
	if  (dp[i]!=-1) return;
	dp[i]=v;
	if(v==1)lefts++;
	else rights++;
	for (int x:adj[i]){
		if(x==p)continue;
		for (int x:adj[i]){
			match(x,i,(v+1)&1);
		}
	}
}

int solve(int i, int p){
	// Either  take  or do not take thsi  value.
	// If we do not take this value, all subtrees are available for taking, so sum up dp across that.
	// If we do take this value, we sum up all secondary subtrees.
	if  (dp[i]==-1){
		int ans1 = 0;
		int ans2 = cost[i];
		for (int x: adj[i]){
			if (x==p||x==i) continue;
			ans1+=solve(x,i);
		}
		for (int x: adj[i]){
			if (x==p||x==i)  continue;
			for (int y: adj[x]){
				if(y==i || y ==p||y==x) continue;
				ans2+=solve(y,x);
			}
		}
		dp[i]=max(ans1,ans2);
	}
	return dp[i];
}



int findSample(int n, int c[], int h[], int p[]){
	int sum = 0;
	for (int i =  0 ; i < n; i++) dp[i] = -1;
	ll mx = 0;
	bool allOne  =  true;
	int prot[3];
	for (int i=  0  ; i < 3; i++)  prot[i]  =  0;
	for (int i = 0 ; i< n; i++) {
		cost[i] = c[i];
		sum  +=  c[i];
		if (c[i]!=1)allOne=false;
		mx = max(mx,cost[i]);
	}
	for (int i =1; i < n; i++){
		prot[p[i]]++;
	}
	int ans = 0;
	if (n <= 10){
		for (int i =1;i<n;i++){
			if(p[i]==1 or p[i]==2){
				for (int x: adj[h[i]]){
					adj[x].push_back(i);
					adj[i].push_back(x);
				}
			}
			if(p[i]==0 or p[i]==2){
				adj[i].push_back(h[i]);
				adj[h[i]].push_back(i);
			}
		}


		for (int bm =0 ; bm < (1<<n); bm++){
			int sum = 0;
			bool works = true;
			bool vis[N];
			for (int i =0 ; i < n; i++) vis[i] = false;
			for (int j =0 ; j < n; j++){
				if ((bm&(1<<j))>0) {
					vis[j]=true;
					sum+=c[j];
				}
			}
			for (int i = 0 ;  i < n;  i++){
				if (vis[i]){
					for (int x:adj[i]) if(vis[x])works=false;
				}
			}
			if (!works)continue;
			ans = max(ans,sum);
		}
	}
	else if (prot[1]==n-1){
		ans  =  sum;
	}
	else if (prot[2]==n-1){
		ans  =  mx;
	}
	else if (prot[0] == n-1){
		for (int i = 1;  i <  n;  i++){
			adj[i].push_back(h[i]);
			adj[h[i]].push_back(i);
		}

		ans = solve(0,0);
	}
	else if(allOne && prot[2]==0){
		//cout<<"YO"<<'\n';
		for (int  i = 1; i  < n; i++){
			if (p[i]==0){
				adj[i].push_back(h[i]);
				adj[h[i]].push_back(i);
			}
			else{
				for (int x:adj[h[i]]){
				adj[i].push_back(x);
				adj[x].push_back(i);
				}
			}
		}

		for (int i  =  0;  i  < n;  i++){
			lefts=0;
			rights=0;
			match(i,i,0);
			ans +=max(lefts,rights);
		}
	}
	return ans;
}

int mains(){
	int n; cin>>n;
	int  c[n], h[n], p[n];
	for (int i = 0; i < n; i++) cin>>c[i];
	for (int i =1 ; i < n; i++)  cin>>h[i]>>p[i];
	cout<<findSample(n,c,h,p)<<'\n';
	return 0;
}

• Subtask 1: 11 / 11
• Subtask 2: 8 / 8
• Subtask 3: 8 / 8
• Subtask 4: 19 / 19
• Subtask 5: 0 / 23
• Subtask 6: 0 / 31