Submission #129900

#	Time	Username	Problem	Language	Result	Execution time	Memory
129900		Abelyan	Cat in a tree (BOI17_catinatree)	C++17	100 / 100	844 ms	331016 KiB

catinatree

#include <bits/stdc++.h>
using namespace std;
 
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
 
#define FOR(i,a) for (int i=0;i<(a);++i)
#define FORD(i,a) for (int i=(a)-1;i>=0;i--)
#define FORT(i,a,b) for (int i=(a);i<=(b);++i)
#define FORTD(i,b,a) for (int i=(b);i>=(a);--i)
#define trav(i,v) for (auto i : v)
#define all(v) v.begin(),v.end()
#define ad push_back
#define fr first
#define sc second
#define mpr(a,b) make_pair(a,b)
#define pir pair<int,int>
#define all(v) v.begin(),v.end()
#define make_unique(v) v.erase(unique(all(v)),v.end())
#define fastio ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define srng mt19937 rng(chrono::steady_clock::now().time_since_epoch().count())
#define y1 EsiHancagorcRepa
 
const int N=2e5+10;
const ll MOD=1e9+7;
 
vector<int> g[N];
int dp[N][406];
int n,d;
 
void dfs(int v,int par=-1){
    vector<int> gum(d),mx(d),suf(d);
    trav(to,g[v]){
        if (to==par)continue;
        dfs(to,v);
        FOR(i,d){
            gum[i]+=dp[to][i];
            if (d-2>=i){
                mx[i]=max(mx[i],dp[to][i]-dp[to][d-2-i]);
            }
        }
    }
    FOR(i,d){
        mx[i]+=gum[d-2-i];
    }
    FORD(i,d/2){
        suf[i]=max(suf[i+1],mx[i]);
    }
    FOR(i,d){
        if (i==0){
            dp[v][i]=max(gum[d-1]+1,suf[0]);
        }
        else if (i>d/2){
            dp[v][i]=gum[i-1];
        }
        else{
            dp[v][i]=suf[i-1];
        }
    }
    /*
    cout<<v<<endl;
    FOR(i,d)cout<<dp[v][i]<<" ";
    cout<<endl;*/
}
 
bool col[N];
vector<pir> srt;
void dfs2(int v,int dep=n,int par=-1){
    srt.ad({dep,v});
    trav(to,g[v]){
        if (to==par)continue;
        dfs2(to,dep-1,v);
    }
}
 
 
void dfs3(int v,int dep=0,int par=-1){
    if (dep>=d)return;
    //cout<<v<<endl;
    col[v]=true;
    trav(to,g[v]){
        if (to==par)continue;
        dfs3(to,dep+1,v);
    }
}
 
 
int main(){
    fastio;
    srng;
    cin>>n>>d;
    if (d>=n){
        cout<<1<<endl;
        return 0;
    }
    FORT(i,1,n-1){
        int p;
        cin>>p;
        g[p].ad(i);
        g[i].ad(p);
    }
    if (d<=400){
        dfs(0);
        cout<<dp[0][0]<<endl;
    }
    else{
        dfs2(0);
        sort(all(srt));
        int ans=0;
        FOR(i,srt.size()){
            int tv=srt[i].sc;
            if (!col[tv]){
                ans++;
                dfs3(tv);
                //cout<<"****"<<endl;
            }
        }
        cout<<ans<<endl;
    }
    return 0;
}

Compilation message (stderr)

catinatree.cpp: In function 'int main()':
catinatree.cpp:8:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 #define FOR(i,a) for (int i=0;i<(a);++i)
                                ^
catinatree.cpp:111:9: note: in expansion of macro 'FOR'
         FOR(i,srt.size()){
         ^~~

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