Submission #106708

#	Time	Username	Problem	Language	Result	Execution time	Memory
106708		tincamatei	Friend (IOI14_friend)	C++14	46 / 100	32 ms	1548 KiB

friend

#include "friend.h"
#include <bits/stdc++.h>

using namespace std;

const int MAX_N = 1000;
bool matr[MAX_N][MAX_N];
vector<int> graph[MAX_N];


void buildGraph(int n, int *host, int *protocol) {
	for(int i = 1; i < n; ++i) {
		if(protocol[i] == 0)
			matr[i][host[i]] = matr[host[i]][i] = true;
		else if(protocol[i] == 1) {
			for(int j = 0; j < n; ++j)
				if(matr[host[i]][j])
					matr[i][j] = matr[j][i] = true;
		} else {
			matr[i][host[i]] = matr[host[i]][i] = true;
			for(int j = 0; j < n; ++j)
				if(matr[host[i]][j])
					matr[i][j] = matr[j][i] = true;
		}
	}

	for(int i = 0; i < n; ++i)
		matr[i][i] = false;

	for(int i = 0; i < n; ++i)
		for(int j = 0; j < n; ++j)
			if(matr[i][j])
				graph[i].push_back(j);
}

int subtask2(int n, int *confidence, int *host, int *protocol) {
	int sum = 0;
	for(int i = 0; i < n; ++i)
		sum += confidence[i];
	return sum;
}

int subtask3(int n, int *confidence, int *host, int *protocol) {
	int rez = 0;
	for(int i = 0; i < n; ++i)
		rez = max(rez, confidence[i]);
	return rez;
}

int dp[MAX_N][2];
void dfs(int *confidence, int nod, int papa = -1) {
	dp[nod][1] = confidence[nod];
	for(auto it: graph[nod])
		if(it != papa) {
			dfs(confidence, it, nod);
			dp[nod][1] += dp[it][0];
			dp[nod][0] += max(dp[it][0], dp[it][1]);
		}
}

int subtask4(int n, int *confidence, int *host, int *protocol) {
	buildGraph(n, host, protocol);
	dfs(confidence, 0);
	return max(dp[0][0], dp[0][1]);
}

bool viz[MAX_N];
vector<int> bip[2];

void dfs(int nod, int color = 0) {
	viz[nod] = true;
	bip[color].push_back(nod);

	for(auto it: graph[nod])
		if(!viz[it])
			dfs(it, 1 - color);
}

int matchsize;
int other[MAX_N];
bool pairup(int nod) {
	if(viz[nod]) return false;
	viz[nod] = true;
	
	for(auto it: graph[nod])
		if(other[it] == -1) {
			other[nod] = it;
			other[it] = nod;
			return true;
		} else if(it != other[nod] && pairup(other[it])) {
			other[nod] = it;
			other[it] = nod;
			return true;
		}
	return false;
}

int subtask5(int n, int *confidence, int *host, int *protocol) {
	buildGraph(n, host, protocol);

	for(int i = 0; i < n; ++i)
		other[i] = -1;
	
	dfs(0);

	bool ok;
	do {
		ok = false;
		for(int i = 0; i < n; ++i)
			viz[i] = false;

		for(auto it: bip[0])
			if(other[it] == -1 && !viz[it]) {
				bool rez = pairup(it);
				ok |= rez;
				matchsize += rez;
			}

	} while(ok);

	return n - matchsize;
}

// Find out best sample
int findSample(int n,int confidence[],int host[],int protocol[]){
	int rez = 0;
	if(n <= 10) {
		buildGraph(n, host, protocol);
		
		for(int mask = 0; mask < (1 << n); ++mask) {
			int sum = 0;
			bool ok = true;
			
			for(int i = 0; i < n; ++i) {
				if((1 << i) & mask)
					sum = sum + confidence[i];
				for(int j = 0; j < n; ++j)
					if(((1 << i) & mask) != 0 && ((1 << j) & mask) != 0 && matr[i][j])
						ok = false;
			}
			if(ok)
				rez = max(rez, sum);
		}
	} else {
		int nr[3];
		nr[0] = nr[1] = nr[2] = 0;

		for(int i = 1; i < n; ++i)
			nr[protocol[i]]++;

		if(nr[0] == 0 && nr[1] == n - 1 && nr[2] == 0)
			rez = subtask2(n, confidence, host, protocol);
		else if(nr[0] == 0 && nr[1] == 0 && nr[2] == n - 1)
			rez = subtask3(n, confidence, host, protocol);
		else if(nr[0] == n - 1 && nr[1] == 0 && nr[2] == 0)
			rez = subtask4(n, confidence, host, protocol);
		else if(nr[2] == 0)
			rez = subtask5(n, confidence, host, protocol);
	}

	return rez;
}

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