Submission #299781

#	Time	Username	Problem	Language	Result	Execution time	Memory
299781		kevlee	Friend (IOI14_friend)	C++17	69 / 100	40 ms	4480 KiB

friend

#include "friend.h"
#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define mod 1000000007
#define h1 7897897897897897
#define h2 7897466719774591
#define b1 98762051
#define b2 98765431
#define inf 1000000000
#define pi 3.1415926535897932384626
#define LMAX 9223372036854775807
#define ll long long
#define fi first
#define se second
#define pii pair<int, int>
#define pll pair<ll, ll>
#define vi vector<int>
#define vl vector<ll>
#define vp vector<pii>
#define SET(a, b) memset(a, b, sizeof(a))
#define all(x) (x).begin(), (x).end()
#define FOR(i, a, b) for (int i = (a); i <= (b); i++)
#define FORD(i, a, b) for (int i = (a); i >= (b); i--)
vi edges[1005];
int dp[1005][2], a[1005], par[1005], dist[1005], color[1005], n, exhaustion, cap[1005][1005];
bool pick[15];
bool vis[1005];
void dfs(int x, int p) {
  dp[x][1] = a[x];
  for (auto y: edges[x]) {
    if (y != p) {
      dfs(y, x);
      dp[x][1] += dp[y][0];
      dp[x][0] += max(dp[y][0], dp[y][1]);
    }
  }
}
void dfs_color(int x, int c) {
  if (color[x]) {
    return;
  }
  color[x] = c;
  for (auto y: edges[x]) {
    dfs_color(y, 3-c);
  }
}
bool bfs() {
  queue <int> q;
  q.push(n);
  SET(vis, false);
  dist[n] = inf;
  vis[n] = true;
  //cout << "start" << endl;
  while (!q.empty()) {
    int f = q.front();
    q.pop();
    //cout << "f = " << f << endl;
    if (f == n+1) return true;
    for (auto y: edges[f]) {
      if (!vis[y] && cap[f][y] > 0) {
        q.push(y);
        vis[y] = true;
        par[y] = f;
        dist[y] = min(dist[f], cap[f][y]);
      }
    }
  }
  return false;
}
int subtask5() {
  int maxflow = 0;
  FOR(i, 0, n-1) {
    if (!color[i]) {
      dfs_color(i, 1);
    }
  }
  //source = n
  //sink = n+1
  FOR(i, 0, n-1) {
    if (color[i] == 1) {
      for (auto y: edges[i]) {
        cap[i][y] = 1;
      }
      edges[n].pb(i);
      edges[i].pb(n);
      cap[n][i] = 1;
    } else {
      edges[n+1].pb(i);
      edges[i].pb(n+1);
      cap[i][n+1] = 1;
    }
  }
  while (true) {
    bool foundpath = bfs();
    if (!foundpath) break;
    int path = dist[n+1];
    //cout << "path = " << path << endl;
    maxflow += path;
    int node = n+1;
    while (node != n) {
      cap[par[node]][node] -= path;
      cap[node][par[node]] += path;
      node = par[node];
    }
  }
  return n - maxflow;
}
int subtask4() {
  dfs(0, -1);
  return max(dp[0][0], dp[0][1]);
}
bool connected(int x, int y) {
  for (auto it: edges[x]) {
    if (it == y) return true;
  }
  return false;
}
void recur(int x) {
  if (x == n) {
    bool ok = true;
    FOR(i, 0, n-1) {
      FOR(j, i+1, n-1) {
        if (pick[i] && pick[j] && connected(i, j)) ok = false;
      }
    }
    if (ok) {
      int cnt = 0;
      FOR(i, 0, n-1) if (pick[i]) cnt += a[i];
      exhaustion = max(exhaustion, cnt);
    }
    return;
  }
  pick[x] = 0;
  recur(x+1);
  pick[x] = 1;
  recur(x+1); 
}
int subtask1() {
  recur(0);
  return exhaustion;
  //return subtask5();
}
int findSample(int N,int confidence[],int host[],int protocol[]){
  n = N;
  FOR(i, 0, n-1) a[i] = confidence[i];
  FOR(i, 1, n-1) {
    if (protocol[i] == 0) {
      edges[i].pb(host[i]);
      edges[host[i]].pb(i);
    } else if (protocol[i] == 1) {
      for (auto y: edges[host[i]]) {
        edges[i].pb(y);
        edges[y].pb(i);
      }
    } else {
      for (auto y: edges[host[i]]) {
        edges[i].pb(y);
        edges[y].pb(i);
      }
      edges[i].pb(host[i]);
      edges[host[i]].pb(i);
    }
  }
  if (n <= 10) {
    return subtask1();
  }
  if (*max_element(a, a+n) == 1) {
    return subtask5();
  }
  if (protocol[1] == 0) {
    return subtask4();
  }
  if (protocol[1] == 1) {
    int sum = 0;
    FOR(i, 0, n-1) {
      sum += a[i];
    }
    return sum;
  }
  return *max_element(a, a+n);
}

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