Submission #363601

#	Time	Username	Problem	Language	Result	Execution time	Memory
363601		silverfish	Friend (IOI14_friend)	C++17	35 / 100	1 ms	492 KiB

friend

#include "friend.h"
#include <bits/stdc++.h>
using namespace std;
 
const int N = 1e3+1;
 
vector<int> adj[N];
long long dp[N][2];
int vis[N], d[N];
 
void dfs(int u, int p, int *conf){
 
	for(int v : adj[u]){
		if(v != p) dfs(v, u, conf);
	}
 
	for(int v : adj[u]){
		if(v != p){
			dp[u][0] += max(dp[v][1], dp[v][0]);
			dp[u][1] += dp[v][0];
		}
	}
	dp[u][1] += 1LL*conf[u];
}
 
int findSample(int n, int conf[],int host[],int protocol[]){
	bool subtask2 = 1, subtask3 = 1, subtask4 = 1, subtask5 = 1;
	for(int i = 1; i < n; ++i){
		if(protocol[i] != 1) subtask2 = 0;
		if(protocol[i] != 2) subtask3 = 0;
		if(protocol[i] != 0) subtask4 = 0;
		if(conf[i] != 1) subtask5 = 0;
	}
	if(subtask2){
		long long ans = 0;
		for(int i = 0; i < n; ++i) ans += 1LL*conf[i];
		return ans;
	}
	if(subtask3){
		return *max_element(conf, conf+n);
	}
 
	if(subtask4){
		//build tree
		for(int i = 1; i < n; ++i){
			adj[host[i]].push_back(i);
			adj[i].push_back(host[i]);
		}
 
		dfs(0, 0, conf);
		return max(dp[0][1], dp[0][0]);
	}
 
	if(subtask5){
 
		for(int i = 1; i < n; ++i){
			if(protocol[i] == 0){
				adj[host[i]].push_back(i);
				adj[i].push_back(host[i]);
			}else{
				for(int j : adj[host[i]]){
					adj[i].push_back(j);
					adj[j].push_back(i);
				}
			}
		}
 
 
		memset(vis, 0, sizeof vis);
		long long ans = 0;

		for(int i = 0; i < n; ++i){
			if(vis[i]) continue;

			array<long long,2> curans = {0LL, 0LL};

			queue<int> q;
			q.push(i);
			d[i] = 0;
			vis[i] = 1;
			// node, depth

			while(q.size()){
				int u = q.front(); q.pop();

				++curans[(d[u]%2)];

				for(int v : adj[u]){
					if(!vis[v]){
						vis[v] = 1;
						d[v] = d[u]+1;
						q.push(v);
					}else if(vis[v]){
						assert(d[v]%2 != d[u]%2);
					}
				}
			}
			ans += max(curans[0], curans[1]);
		}
		return ans;
	}
 
	return -1;
}

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