Submission #474017

#	Time	Username	Problem	Language	Result	Execution time	Memory
474017		julian33	Cat in a tree (BOI17_catinatree)	C++14	51 / 100	108 ms	56108 KiB

catinatree

#include <bits/stdc++.h>

using namespace std;

#ifdef LOCAL
#define deb(...) logger(#__VA_ARGS__, __VA_ARGS__)
template<typename ...Args>
void logger(string vars, Args&&... values) {
    cerr<<vars<<" = ";
    string delim="";
    (...,(cerr<<delim<<values,delim=", "));
    cerr<<"\n";
}
#else
#define deb(...) logger(#__VA_ARGS__, __VA_ARGS__)
template<typename ...Args>
void logger(string vars, Args&&... values) {}
#endif

#define pb push_back
#define sz(x) (int)(x.size())
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
template<typename T> inline void maxa(T& a,T b){a=max(a,b);}
template<typename T> inline void mina(T& a,T b){a=min(a,b);} 
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int mxN=2e5+5,mxL=19; //make sure this is right
const int mod=1e9+7;

vector<int> graph[mxN],path;
int bad[mxN],ht[mxN],seen[mxN];
priority_queue<pii> q;
int up[mxN][mxL];

void dfs(int at,int p=-1){
    up[at][0]=~p?p:at;
    for(int i=1;i<mxL;i++)
        up[at][i]=up[up[at][i-1]][i-1];
    for(int &i:graph[at]){
        if(i==p)
            continue;
        ht[i]=ht[at]+1;
        dfs(i,at);
    }
    q.push({ht[at],at});
}

int jump(int a,int k){
    for(int i=0;i<mxL;i++){
        if(k&(1<<i))
            a=up[a][i];
    }
    return a;
}

int lca(int a,int b){
    if(ht[a]>ht[b])
        swap(a,b);
    b=jump(b,ht[b]-ht[a]);
    if(a==b)
        return a;
    for(int i=mxL-1;i>=0;i--){
        if(up[a][i]!=up[b][i]){
            a=up[a][i];
            b=up[b][i];
        }
    }
    return up[a][0];
}

void paint(int at,int d,int dep){
    if(d==0 || ht[at]>dep || seen[at])
        return;
    bad[at]=1;
    seen[at]=1;
    path.pb(at);
    for(int &i:graph[at])
        paint(i,d-1,dep);
}

int main(){
    cin.sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    #ifdef LOCAL
        freopen("input.txt","r",stdin);
        freopen("output.txt","w",stdout);
    #endif

    int n,d; cin>>n>>d;
    for(int i=1;i<n;i++){
        int x; cin>>x;
        graph[x].pb(i);
        graph[i].pb(x);
    }
    dfs(0);
    int ans=0;
    vector<int> used;
    while(!q.empty()){
        int at=q.top().second; q.pop();
        if(d<=200){
            assert(n<1e5);
            if(bad[at])
                continue;
            ans++;
            paint(at,d,ht[at]);
            while(sz(path)){
                seen[path.back()]=0;
                path.pop_back();
            }
        } else{
            int no=0;
            for(int &i:used){
                if(ht[at]+ht[i]-2*ht[lca(at,i)]<d){
                    no=1; break;
                }
            }
            if(no)
                continue;
            ans++;
            used.pb(at);
        }
    }
    cout<<ans<<"\n";
}

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