Submission #897932

#	Time	Username	Problem	Language	Result	Execution time	Memory
897932		nnhzzz	Cat in a tree (BOI17_catinatree)	C++14	11 / 100	3 ms	12892 KiB

catinatree

/* [Author: Nguyen Ngoc Hung] - From THPT Ngo Gia Tu with Love */

#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <locale>
#include <map>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <unordered_set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <utility>
#include <valarray>
#include <vector>
#include <cstring>
#include <unordered_map>
#include <cmath>
#include <array>
#include <cassert>
#include <random>
#include <chrono>

using namespace std;

#define        __nnhzzz__  signed main()
#define          BIT(i,j)  (((i)>>(j))&1LL)
#define           MASK(i)  (1LL<<(i))
#define            ALL(x)  (x).begin(),(x).end()
#define             SZ(x)  (int)(x).size()
#define                fi  first
#define                se  second
#define                ll  long long
#define                ld  long double
#define                vi  vector<int>
#define               vvi  vector<vi>
#define              vvvi  vector<vvi>
#define               pii  pair<int,int>
#define              vpii  vector<pii>
#define             vvpii  vector<vpii>
#define REPDIS(i,be,en,j)  for(int i = (be); i<=(en); i+=j)
#define     REPD(i,be,en)  for(int i = (be); i>=(en); i--)
#define      REP(i,be,en)  for(int i = (be); i<=(en); i++)
#define              endl  "\n"
#define                MP  make_pair
// #define               int  ll

//-----------------------------------------------------------------------------------------------//
int readInt(){
    char c;
    do{ c = getchar(); }while(c!='-' && !isdigit(c));
    bool neg = (c=='-');
    int res = neg?0:c-'0';
    while(isdigit(c=getchar())) res = (res<<3)+(res<<1)+(c-'0');
    return neg?-res:res;
}
//------------------------------------------------------------------------------------------------//
const  ll   LINF = 1e18;
const int    INF = 1e9;
const int    LOG = 20;
const int   MAXN = 2e5+7;
const int      N = 1e2+3;
const int    MOD = 1e9+7;
const int   BASE = 1e5;
const  ld    EPS = 1e-9;
const  ld     PI = acos(-1);
const int OFFSET = 1e3;
//------------------------------------------------------------------------------------------------//
template<typename T1, typename T2> bool mini(T1 &a, T2 b){if(a>b){a=b;return true;}return false;}
template<typename T1, typename T2> bool maxi(T1 &a, T2 b){if(a<b){a=b;return true;}return false;}
template<typename T> T gcd(T a, T b) { while(b) { a %= b; swap(a,b); } return a; }
template<typename T> T lcm(T a, T b) { return a/gcd(a,b)*b; }
//------------------------------------------------------------------------------------------------//

/*
----------------------------------------------------------------
    END OF TEMPLATE
----------------------------------------------------------------
    Nguyen Ngoc Hung - nnhzzz
    Training for VOI24 gold medal
----------------------------------------------------------------
*/

vi adj[MAXN],dp[MAXN];
int n,d;

namespace sub1{
    int h[MAXN],tmp[MAXN];

    void dfs(int u, int par){
        dp[u].push_back(1);
        for(int &v:adj[u]){
            if(v==par) continue;
            dfs(v,u);
            maxi(h[u],h[v]+1);
            dp[u].resize(min(d+1,h[u]+1));
            REP(i,0,SZ(dp[u])-1){
                tmp[i] = dp[u][i];
            }
            REP(j,0,SZ(dp[v])-1){
                maxi(tmp[j+1],dp[v][j]);
            }
            REP(i,0,SZ(dp[u])-1){
                REP(j,max(0,d-i-1),SZ(dp[v])-1){
                    int MIN = min(i,j+1);
                    maxi(tmp[MIN],dp[u][i]+dp[v][j]);
                }
            }
            REP(i,0,SZ(dp[u])-1) dp[u][i] = tmp[i];
        }
    }

    void solve(){
        dfs(1,0);
        int res = 0;
        for(int &i:dp[1]) maxi(res,i);
        cout << res;
    }
}

namespace sub2{
    int child[MAXN],tmp[MAXN];

    void dfs(int u, int par){
        dp[u].resize(2);
        dp[u][1] = 0; child[u] = 1;
        for(int &v:adj[u]){
            if(v==par) continue;
            dfs(v,u);
            int siz = max(2,min(n/d+1,child[u]+1));
            dp[u].resize(siz,-INF);
            REP(i,0,SZ(dp[u])-1) tmp[i] = dp[u][i];
            REP(i,0,SZ(dp[v])-1){
                if(dp[v][i]==-INF) break;
                maxi(tmp[i],dp[v][i]+1);
            }
            REP(i,1,SZ(dp[u])-1){
                if(dp[u][i]==-INF) break;
                REP(j,1,SZ(dp[v])-1){
                    if(dp[v][j]==-INF) break;
                    if(dp[u][i]+dp[v][j]+1<d) continue;
                    maxi(tmp[i+j],min(dp[u][i],dp[v][j]+1));
                }
            }
            REP(i,0,SZ(dp[u])-1) dp[u][i] = tmp[i];
        }
    }

    void solve(){
        dfs(1,0);
        REPD(i,SZ(dp[1])-1,1){
            if(dp[1][i]!=-INF) continue;
            cout << i;
            return ;
        }
    }
}

void solve(){
    cin >> n >> d;
    REP(u,2,n){
        int v; cin >> v; ++v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    if(n<=20 || d<=n/d){
        sub1::solve();
        return ;
    }
    sub2::solve();
}

__nnhzzz__{
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    #define task "test"
    if(fopen(task".inp","r")){
        freopen(task".inp","r",stdin);
        freopen(task".out","w",stdout);
    }
    #define task1 "nnhzzz"
    if(fopen(task1".inp","r")){
        freopen(task1".inp","r",stdin);
        freopen(task1".out","w",stdout);
    }

    int test = 1;

    while(test--){
      solve();
    }
    cerr << "\nTime elapsed: " << 1000*clock()/CLOCKS_PER_SEC << "ms\n";
    return 0;
}

/**  /\_/\
 *  (= ._.)
 *  / >TL \>AC
**/

Compilation message (stderr)

catinatree.cpp: In function 'int main()':
catinatree.cpp:195:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  195 |         freopen(task".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
catinatree.cpp:196:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  196 |         freopen(task".out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
catinatree.cpp:200:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  200 |         freopen(task1".inp","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
catinatree.cpp:201:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  201 |         freopen(task1".out","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

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