Submission #850203

#	Time	Username	Problem	Language	Result	Execution time	Memory
850203		ThMinh_	Cat in a tree (BOI17_catinatree)	C++14	100 / 100	60 ms	24236 KiB

catinatree

#include<bits/stdc++.h>
#define forin(i, a, b) for(int i = a; i <= b; ++i)
using namespace std;
const int N = 2e5 + 10;
int n, d;
int g[N], f[N], cnt[N];
vector<int> adj[N];
void dfs(int u = 1, int p = 0) {
   f[u] = 1e9;
   for(auto v : adj[u]) if(v != p) {
      dfs(v, u);
      cnt[u] += cnt[v];
      f[u] = min(f[u], f[v] + 1);
      if(g[v]) {
         if(g[v] * 2 >= d) {
            f[u] = min(f[u], g[v] + 1);
            cnt[u]++;
         }
         else g[u] = max(g[u], g[v] + 1);
      }
   }
   if(g[u] + f[u] - 2 < d) g[u] = 0;
   if(!g[u] && f[u] - 1 >= d) g[u] = 1;
}
int main () {
   cin.tie(0)->sync_with_stdio(0);
   if(fopen("Task.inp","r")) {
      freopen("Task.inp","r",stdin);
      freopen("WA.out","w",stdout);
   }
   if(fopen("Durian.inp","r")) {
      freopen("Durian.inp","r",stdin);
      freopen("Durian.out","w",stdout);
   }
   cin>>n>>d;
   forin(i, 1, n - 1) {
      int x; cin>>x;
      adj[i + 1].push_back(x + 1);
      adj[x + 1].push_back(i + 1);
   }
//   forin(i, 1, n - 1) {
//      int u, v; cin>>u>>v;
//      adj[u].push_back(v);
//      adj[v].push_back(u);
//   }
   dfs();
   cout<<cnt[1] + bool (g[1]);
}

Compilation message (stderr)

catinatree.cpp: In function 'int main()':
catinatree.cpp:28:14: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   28 |       freopen("Task.inp","r",stdin);
      |       ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
catinatree.cpp:29:14: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   29 |       freopen("WA.out","w",stdout);
      |       ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
catinatree.cpp:32:14: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   32 |       freopen("Durian.inp","r",stdin);
      |       ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
catinatree.cpp:33:14: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   33 |       freopen("Durian.out","w",stdout);
      |       ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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