Submission #73854

#	Time	Username	Problem	Language	Result	Execution time	Memory
73854		funcsr	Friend (IOI14_friend)	C++17	69 / 100	142 ms	17408 KiB

friend

#include "friend.h"
#include <vector>
#include <cassert>
#define rep(i, n) for (int i=0; i<(n); i++)
#define pb push_back
using namespace std;
typedef pair<int, int> P;

vector<int> Gchildren[200000];
vector<int> Gclone[200000];
int repr[100000];
int W[200000];
bool both[200000];

int dp0[200000], dp1[200000];
void dfs(int x, int p) {
  dp0[x] = 0, dp1[x] = W[x];
  for (int t : Gchildren[x]) if (t != p) {
    dfs(t, x);
    dp0[x] += dp1[t];
    dp1[x] += dp0[t];
  }
  if (!Gclone[x].empty()) {
    assert(Gclone[x].size() == 2);
    int t1 = Gclone[x][0], t2 = Gclone[x][1];
    dfs(t1, x);
    dfs(t2, x);
    dp0[x] += dp0[t1]+dp0[t2];
    if (both[x]) dp1[x] += dp1[t1]+dp1[t2];
    else dp1[x] += max(dp1[t1]+dp0[t2], dp0[t1]+dp1[t2]);
  }
  dp1[x] = max(dp1[x], dp0[x]);
}

int findSample(int N, int A[], int host[], int protocol[]) {
  W[0] = A[0];
  repr[0] = 0;
  int V = 1;
  for (int i=1; i<N; i++) {
    int p = host[i];
    if (protocol[i] == 0) {
      Gchildren[repr[p]].pb(V);
      W[V] = A[i];
      repr[i] = V;
      V++;
    }
    else {
      // copy
      int root = repr[p], p_new = V++, x = V++;
      repr[p] = p_new;
      repr[i] = x;

      W[p_new] = W[root];
      W[x] = A[i];
      W[root] = 0;

      Gclone[root].pb(p_new);
      Gclone[root].pb(x);

      both[root] = protocol[i] == 1;
    }
  }

  dfs(0, -1);
  return dp1[0];
}

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