Submission #129655

#	Time	Username	Problem	Language	Result	Execution time	Memory
129655		Vardanyan	Cat in a tree (BOI17_catinatree)	C++14	100 / 100	872 ms	330232 KiB

catinatree

#include <bits/stdc++.h>
using namespace std;
#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)
const int N = 2*1000*100+5;
vector<int> g[N];
int mark[N];
int depth[N];
void dfs(int v,int p = -1){
   if(p!=-1) depth[v] = depth[p]+1;
    for(int i = 0;i<g[v].size();i++){
        int to = g[v][i];
        if(to == p) continue;
        dfs(to,v);
    }

}
bool cmp(int a,int b){
    return depth[a]>depth[b];
}
bool col[N];
int d;
void go(int v,int dd = 0,int p = -1){
    if(dd>=d) return;
    mark[v] = 1;
    for(int i = 0;i<g[v].size();i++){
        int to = g[v][i];
        if(to == p) continue;
        go(to,dd+1,v);
    }
}
int dp[N][405];


void dfss(int v,int par=-1){
    vector<int> gum(d),mx(d),suf(d);
    for(int i = 0;i<g[v].size();i++){
        int to = g[v][i];
        if (to==par)continue;
        dfss(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;*/
}

int main(){
    ios_base::sync_with_stdio(false);
    int n;
    cin>>n>>d;
    for(int i = 1;i<=n-1;i++){
        int x;
        cin>>x;
        g[i].push_back(x);
        g[x].push_back(i);
    }
    long long x = n*n/d;
    long long y = n*d;
    if(d<401){
        dfss(0);
        cout<<dp[0][0]<<endl;
        return 0;
    }
    dfs(0);
    vector<int> v;
    for(int i = 0;i<n;i++) v.push_back(i);
    sort(v.begin(),v.end(),cmp);
    int ans = 0;
    int num = 1;
    for(int jj = 0;jj<n;jj++){
        int i = v[jj];
        if(mark[i]) continue;
        mark[i] = 1;
        ans++;
        go(i);
        /*queue<pair<int,int> > q;
        q.push({i,0});
        num++;
        col[i] = num;
        while(!q.empty()){
            pair<int,int> x = q.front();
            int gag = x.first;
            int dd = x.second;
            q.pop();
            if(dd>=d) continue;
            mark[gag] = 1;

            for(int j = 0;j<g[gag].size();j++){
                int to = g[gag][j];
                if(col[to]!=num){
                    q.push({to,dd+1});
                    col[to] = num;
                }
            }
        }*/
 //       for(int i = 0;i<n;i++) cout<<mark[i]<<" ";
 //       cout<<endl;
    }
    cout<<max(1,ans)<<endl;
    return 0;
}

Compilation message (stderr)

catinatree.cpp: In function 'void dfs(int, int)':
catinatree.cpp:13:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0;i<g[v].size();i++){
                   ~^~~~~~~~~~~~
catinatree.cpp: In function 'void go(int, int, int)':
catinatree.cpp:28:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0;i<g[v].size();i++){
                   ~^~~~~~~~~~~~
catinatree.cpp: In function 'void dfss(int, int)':
catinatree.cpp:39:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0;i<g[v].size();i++){
                   ~^~~~~~~~~~~~
catinatree.cpp: In function 'int main()':
catinatree.cpp:83:15: warning: unused variable 'x' [-Wunused-variable]
     long long x = n*n/d;
               ^
catinatree.cpp:84:15: warning: unused variable 'y' [-Wunused-variable]
     long long y = n*d;
               ^
catinatree.cpp:95:9: warning: unused variable 'num' [-Wunused-variable]
     int num = 1;
         ^~~

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