제출 #115771

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
115771		thecodingwizard	Friend (IOI14_friend)	C++11	38 / 100	379 ms	65536 KiB

friend

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

using namespace std;

#define FOR(a, b, c) for (int a = b; a < c; a++)
#define ll long long
#define vi vector<int>
#define pb push_back
#define mp make_pair

int memo[1000][2];
set<int> friends[1000];
bool visited[1000];
int *A;
void dfsVisited(int u, int p) {
	visited[u] = true;
	for (int v : friends[u]) {
		if (v == p || v == u) continue;
		dfsVisited(v, u);
	}
}
int run(int u, int canTake, int p) {
	if (memo[u][canTake] != -1) return memo[u][canTake];
	int ans = 0;
	// Option 1: Don't take u
	int opAns = 0;
	for (int v : friends[u]) {
		if (v == p || v == u) continue;
		opAns += run(v, 1, u);
	}
	ans = opAns;

	// Option 2: Take u
	if (canTake) {
		opAns = A[u];
		for (int v : friends[u]) {
			if (v == p || v == u) continue;
			opAns += run(v, 0, u);
		}
		ans = max(ans, opAns);
	}
	return memo[u][canTake] = ans;
}

// Find out best sample
int findSample(int n, int confidence[], int host[], int protocol[]) {
	A = confidence;
	FOR(i, 1, n) {
		int h = host[i], p = protocol[i];
		if (p == 0) {
			// IAmYourFriend
			friends[i].insert(h);
			friends[h].insert(i);
		} else if (p == 1) {
			// MyFriendsAreYourFriends
			for (int u : friends[h]) {
				friends[u].insert(i);
				friends[i].insert(u);
			}
		} else {
			// WeAreYourFriends
			friends[i].insert(h);
			friends[h].insert(i);
			for (int u : friends[h]) {
				friends[u].insert(i);
				friends[i].insert(u);
			}
		}
	}

	if (n <= 10) {
		// Subtask 1
		int ans = 0;
		for (int i = 0; i < (1 << n); i++) {
			int curAns = 0;
			bool invalid = false;
			for (int j = 0; j < n; j++) {
				if (!(i & (1 << j))) continue;
				for (int f : friends[j]) {
					if (f == j) continue;
					if (i & (1 << f)) {
						invalid = true;
						break;
					}
				}
				if (invalid) break;
				curAns += confidence[j];
			}
			if (!invalid) ans = max(ans, curAns);
		}
		return ans;
	} else {
		bool isSubtaskTwo = true;
		for (int i = 1; i < n; i++) {
			if (protocol[i] != 1) isSubtaskTwo = false;
		}
		if (isSubtaskTwo) {
			// Subtask two: Sum all confidence values
			int ans = 0;
			for (int i = 0; i < n; i++) ans += confidence[i];
			return ans;
		}

		bool isSubtaskThree = true;
		for (int i = 1; i < n; i++) {
			if (protocol[i] != 2) isSubtaskThree = false;
		}
		if (isSubtaskThree) {
			// Subtask Three: We Are Your Friends, entire graph is connected
			int ans = 0;
			for (int i = 0; i < n; i++) ans = max(ans, confidence[i]);
			return ans;
		}

		// Subtask Four: Tree
		// Define dp[i][0] = max confidence of subtree of i, cannot take i
		//        dp[i][1] = max confidence of subtree of i, can take i
		for (int i = 0; i < n; i++) visited[i] = false;
		for (int i = 0; i < n; i++) memo[i][0] = memo[i][1] = -1;
		int ans = 0;
		for (int i = 0; i < n; i++) {
			if (!visited[i]) {
				dfsVisited(i, i);
				ans += run(i, 1, i);
			}
		}
		return ans;
	}
	exit(1);
}

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