Submission #1019887

#	Time	Username	Problem	Language	Result	Execution time	Memory
1019887		NValchanov	Friend (IOI14_friend)	C++17	38 / 100	117 ms	65536 KiB

friend

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

using namespace std;

typedef long long ll;

const int MAXN = 1e5 + 10;

vector < int > adj[MAXN];
int dp[MAXN][2];
bool visited[MAXN];

void build_graph(int n, int p[], int type[])
{
    for(int i = 1; i < n; i++)
    {
        if(type[i] == 0)
        {
            adj[i].push_back(p[i]);
            adj[p[i]].push_back(i);
        }
        else if(type[i] == 1)
        {
            for(int v : adj[p[i]])
            {
                adj[v].push_back(i);
                adj[i].push_back(v);
            }
        }
        else if(type[i] == 2)
        {
            for(int v : adj[p[i]])
            {
                adj[v].push_back(i);
                adj[i].push_back(v);
            }

            adj[i].push_back(p[i]);
            adj[p[i]].push_back(i);
        }
    }
}

int bruteforce(int n, int c[])
{
    int ans = 0;

    for(int mask = 1; mask < (1 << n); mask++)
    {
        bool lampa = false;

        for(int i = 0; i < n; i++)
        {
            if(mask & (1 << i))
            {
                for(int v : adj[i])
                {
                    if(mask & (1 << v))
                        lampa = true;
                }
            }
        }

        if(lampa)
            continue;

        int sum = 0;

        for(int i = 0; i < n; i++)
        {
            if(mask & (1 << i))
                sum += c[i];
        }

        ans = max(ans, sum);
    }

    return ans;
}

void dfs(int u, int par, int c[])
{
    visited[u] = true;
    dp[u][1] = c[u];

    for(int v : adj[u])
    {
        if(v == par)
            continue;

        dfs(v, u, c);

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

int solve_dp(int n, int c[])
{
    int ans = 0;

    for(int i = 0; i < n; i++)
    {
        if(!visited[i])
        {
            dfs(i, i, c);
            ans += max(dp[i][0], dp[i][1]);
        }
    }

    return ans;
}

int findSample(int n, int c[], int p[], int type[])
{
    build_graph(n, p, type);

    if(n <= 10)
        return bruteforce(n, c);
    else
        return solve_dp(n, c);
}

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