Submission #827810

#	Time	Username	Problem	Language	Result	Execution time	Memory
827810		mychecksedad	Cat in a tree (BOI17_catinatree)	C++17	0 / 100	12 ms	23764 KiB

catinatree

/* Author : Tr3nity  */
#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define mod1 (1000000000+7)
#define mod (998244353)
#define pb push_back
#define all(x) x.begin(), x.end()
#define mp make_pair
#define en cout << '\n'
const int N = 1e6+100, M = 1e5+10, K = 18;

struct dp{
  int val, dist, next;
};

int n, d;
vector<int> g[N];
dp a[N];


void update(int v, int x, int dep, int nxt){
  if(x > a[v].val){
    a[v].val = x;
    a[v].dist = dep;
    a[v].next = nxt;
  }else if(x == a[v].val && dep > a[v].dist){
    a[v].dist = dep;
    a[v].next = nxt;
  }
}

void dfs(int v){
  int sum = 0, small = 0, biggest_small = -1, smallest_big = d, next_smallest = d;
  for(int u: g[v]){
    dfs(u);
    sum += a[u].val;
    if(a[u].dist < (d+1)/2){
      small++;
      if(biggest_small == -1 || a[biggest_small].dist < a[u].dist){
        biggest_small = u;
      }
      if(smallest_big > a[u].next)
        next_smallest = smallest_big, smallest_big = a[u].next;
    }else if(d % 2 == 0 && a[u].dist == d / 2){
      biggest_small = u;
    }
    if((d+1)/2 <= a[u].dist){
      if(smallest_big > a[u].dist)
        next_smallest = smallest_big, smallest_big = a[u].dist;
      if(next_smallest > a[u].next)
        next_smallest = a[u].next;
    }
  }
  if(g[v].size() == 0){
    a[v].val = 1, a[v].dist = 1;
    return;
  }
  bool put = min(next_smallest, smallest_big) == d;
  update(v, sum - small + put, (put ? 0 : smallest_big), (put ? d : next_smallest));
  if(biggest_small != -1)
    update(v, sum - small + !(a[biggest_small].dist == d/2 && d%2==0), a[biggest_small].dist, 
      min({a[v].dist, a[biggest_small].next, smallest_big, next_smallest}));
  a[v].dist++;
  a[v].next++;
}

void solve(){
  cin >> n >> d;
  for(int i = 1; i <= n-1; ++i){
    int x; cin >> x;
    g[x].pb(i);
  }   
  for(int i = 0; i < n; ++i) a[i].val = 0, a[i].dist = d, a[i].next = d;
  dfs(0);
  cout << a[0].val;
}


int main(){
  cin.tie(0); ios::sync_with_stdio(0);
  int tt = 1, aa;
  // freopen("in.txt", "r", stdin);
  // freopen("out.txt", "w", stdout);
  // cin >> tt;aa=tt;
  while(tt--){
    solve();
  }
  cerr<<"time taken : "<<(float)clock()/CLOCKS_PER_SEC<<" seconds\n";
  return 0;
}

Compilation message (stderr)

catinatree.cpp: In function 'int main()':
catinatree.cpp:82:15: warning: unused variable 'aa' [-Wunused-variable]
   82 |   int tt = 1, aa;
      |               ^~

• Subtask 1: 0 / 11
• Subtask 2: 0 / 40
• Subtask 3: 0 / 49