Submission #706643

#	Time	Username	Problem	Language	Result	Execution time	Memory
706643		Pety	Logičari (COCI21_logicari)	C++14	110 / 110	150 ms	26896 KiB

Main

#include <bits/stdc++.h>

using namespace std;

int n, p[100002], node1, node2;
vector<int>G[100002];
int preset[100002];
long long dp[100002][2][2];

int find (int x) {
  if (p[x] == x)
    return x;
  return p[x] = find(p[x]);
}

void dfs (int nod, int par) {
  vector<int>sons;
  for (auto it : G[nod])
    if (it != par) {
      sons.push_back(it);
      dfs(it, nod);
    }
  for (int cul = 0; cul < 2; cul++)
    for (int cul2 = 0; cul2 < 2; cul2++) {
      if (cul2 && nod == 1)
        continue;
      if (preset[nod] != -1 && preset[nod] != cul)
        continue;
      int blue = (cul2 + (preset[nod] != -1 && preset[node1 + node2 - nod] == 1));
      if (blue == 2 && par == node1 + node2 - nod)
        blue--;
      if (blue == 2)
        continue;
      dp[nod][cul][cul2] = 0;
      for (auto it : sons)
        dp[nod][cul][cul2] += dp[it][0][cul];
      if (!blue) {
        long long add = -1e9;
        for (auto it : sons)
          add = max(add, dp[it][1][cul] - dp[it][0][cul]);
        dp[nod][cul][cul2] += add;
      }
      dp[nod][cul][cul2] += (!cul);
    }
}

void reset() {
  for (int k = 1; k <= n; k++)
    for (int i = 0; i < 2; i++)
      for (int j = 0; j < 2; j++)
        dp[k][i][j] = -1e9;
}

int main () 
{
  ios_base::sync_with_stdio(false);
  cin.tie(0); cout.tie(0);
  cin >> n;
  for (int i = 1; i <= n; i++)
    p[i] = i;
  for (int i = 1; i <= n; i++) {
    int x, y;
    cin >> x >> y;
    if (find(x) == find(y)) 
      node1 = x, node2 = y;
    else {
      G[x].push_back(y);
      G[y].push_back(x);
    }
    p[find(x)] = find(y);
  }
  memset(preset, -1, sizeof(preset));
  long long ans = 1e18;
  for (int i = 0; i < 2; i++)
    for (int j = 0; j < 2; j++) {
      reset();
      preset[node1] = i;
      preset[node2] = j;
      dfs(1, 0);
      ans = min(ans, n - max(dp[1][0][0], dp[1][1][0]));
    }
  cout << (ans >= n ? -1 : ans);
  return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 40 / 40
• Subtask 4: 50 / 50