Submission #357717

#	Time	Username	Problem	Language	Result	Execution time	Memory
357717		spatarel	Cat in a tree (BOI17_catinatree)	C++17	100 / 100	353 ms	245100 KiB

catinatree

#include <stdio.h>
#include <algorithm>
#include <deque>
#include <vector>

const int MAX_N = 200000;

int N, D;
std::vector<int> children[MAX_N];

std::deque<int> maxN[MAX_N];
int depth[MAX_N];

void dfs(int u) {
  depth[u] = 1;
  int deepestChild = -1;
  int secondDepth = 0;
  for (int v : children[u]) {
    dfs(v);
    if (depth[u] <= 1 + depth[v]) {
      secondDepth = depth[u];
      depth[u] = 1 + depth[v];
      deepestChild = v;
    } else if (secondDepth < 1 + depth[v]) {
      secondDepth = 1 + depth[v];
    }
  }
  
  std::vector<int> maxAdd(secondDepth);
  for (int v : children[u]) {
    for (int d = 0; d < D - d - 2 && d < depth[v] && d + 1 < secondDepth; d++) {
      maxAdd[d + 1] = std::max(maxAdd[d + 1],
          maxN[v][d] - (D - d - 2 < depth[v] ? maxN[v][D - d - 2] : 0));
    }
  }
  int maxNU0 = 1;
  for (int v : children[u]) {
    if (depth[v] > D - 1) {
      maxNU0 += maxN[v][D - 1];
    }
  }
  if (deepestChild != -1) {
    std::swap(maxN[u], maxN[deepestChild]);
  }
  maxN[u].push_front(maxNU0);
  for (int v : children[u]) {
    if (v != deepestChild) {
      for (int d = 0; d < D && d < depth[v]; d++) {
        maxN[u][d + 1] += maxN[v][d];
      }
    }
  }
  for (int d = 0; d + 1 < secondDepth && d < D - d - 2; d++) {
    maxN[u][d + 1] = maxAdd[d + 1] + (D - d - 1 < depth[u] ? maxN[u][D - d - 1] : 0);
  }
  for (int d = secondDepth; d >= 1; d--) {
    maxN[u][d - 1] = std::max(maxN[u][d - 1], maxN[u][d]);
  }
  /*
  printf("maxN[%d] = {", u);
  for (int d = 0; d < D && d < depth[u]; d++) {
    printf("%d, ", maxN[u][d]);
  }
  printf("}\n");
  fflush(stdout);//*/
}

int main() {
  scanf("%d%d", &N, &D);
  for (int i = 1; i < N; i++) {
    int xi;
    scanf("%d", &xi);
    children[xi].push_back(i);
  }
  dfs(0);
  int answer = maxN[0][0];
  printf("%d\n", answer);
  return 0;
}

Compilation message (stderr)

catinatree.cpp: In function 'int main()':
catinatree.cpp:69:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   69 |   scanf("%d%d", &N, &D);
      |   ~~~~~^~~~~~~~~~~~~~~~
catinatree.cpp:72:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   72 |     scanf("%d", &xi);
      |     ~~~~~^~~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 40 / 40
• Subtask 3: 49 / 49