Submission #587053

#	Time	Username	Problem	Language	Result	Execution time	Memory
587053		Jomnoi	Friend (IOI14_friend)	C++17	0 / 100	25 ms	5360 KiB

friend

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

const int MAX_N = 1e5 + 5;

int N, C[MAX_N];
int dp[MAX_N][2];
vector <int> graph[MAX_N];
bool visited[MAX_N];

void dfs(int u) {
	dp[u][1] = C[u];
	for(auto v : graph[u]) {
		dfs(v);

		dp[u][0] += max(dp[v][0], dp[v][1]);
	}

	for(auto v : graph[u]) {
		dp[u][1] = max(dp[u][1], dp[u][0] - max(dp[v][0], dp[v][1]) + dp[v][0] + C[u]);
	}
}

void connect(int s, int x) {
	fill(visited, visited + N, false);

	queue <int> q;
	q.push(s);
	visited[s] = true;
	vector <int> need;
	while(!q.empty()) {
		int u = q.front();
		q.pop();

		for(auto v : graph[u]) {
			if(visited[v] == false) {
				visited[v] = true;
				need.push_back(v);
				q.push(v);
			}
		}
	}

	for(auto v : need) {
		graph[v].push_back(x);
		graph[x].push_back(v);
	}
}

// Find out best sample
int findSample(int n, int confidence[], int host[], int protocol[]){
	N = n;
	int cnt[3] = {};
	for(int i = 0; i < n; i++) {
		C[i] = confidence[i];
	}
	for(int i = 1; i < n; i++) {
		cnt[protocol[i]]++;
	}

	int ans = 0;
	if(n <= 10) {
		for(int i = 1; i < n; i++) {
			if(protocol[i] == 0) {
				graph[host[i]].push_back(i);
				graph[i].push_back(host[i]);
			}
			else if(protocol[i] == 1) {
				connect(host[i], i);
			}
			else if(protocol[i] == 2) {
				connect(host[i], i);
				graph[host[i]].push_back(i);
				graph[i].push_back(host[i]);
			}
		}

		for(int mask = 0; mask < (1<<n); mask++) {
			set <int> consider;
			int sum = 0;
			for(int i = 0; i < n; i++) {
				if(mask & (1<<i)) {
					sum += C[i];
					consider.insert(i);
				}
			}

			for(auto u : consider) {
				for(auto v : graph[u]) {
					if(consider.count(v)) {
						sum = 0;
					}
				}
			}
			ans = max(ans, sum);
		}
	}
	else if(cnt[0] == n) {
		for(int i = 1; i < n; i++) {
			graph[host[i]].push_back(i);
		}

		dfs(0);

		ans = max(dp[0][0], dp[0][1]);
	}
	else if(cnt[1] == n) {
		for(int i = 0; i < n; i++) {
			ans += confidence[i];
		}
	}
	else if(cnt[2] == n) {
		for(int i = 0; i < n; i++) {
			ans = max(ans, confidence[i]);
		}
	}
	else {
		// do something
	}
	return ans;
}

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