Submission #746773

#	Time	Username	Problem	Language	Result	Execution time	Memory
746773		GrindMachine	Cat in a tree (BOI17_catinatree)	C++17	11 / 100	35 ms	35788 KiB

catinatree

// Om Namah Shivaya

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x, y) ((x + y - 1) / (y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl

#define rep(i, n) for(int i = 0; i < n; ++i)
#define rep1(i, n) for(int i = 1; i <= n; ++i)
#define rev(i, s, e) for(int i = s; i >= e; --i)
#define trav(i, a) for(auto &i : a)

template<typename T>
void amin(T &a, T b) {
    a = min(a, b);
}

template<typename T>
void amax(T &a, T b) {
    a = max(a, b);
}

#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif

/*



*/

const int MOD = 1e9 + 7;
const int N = 1500 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;

vector<ll> adj[N];
ll n,d;
ll dp[N][N][2]; // dp[u][j][0/1] = max #of nodes that can be picked in the subtree of u satisfying the condition if the depth of the closest node to u in the subtree is j and 3rd state represents if any guy with depth = j is taken or not

void dfs(ll u, ll p){
    dp[u][0][1] = 1;

    trav(v,adj[u]){
        dfs(v, u);

        vector<ll> suff(n+5);
        rev(j,n,0){
            suff[j+1] = dp[v][j][1];    
        }
        rev(j,n,0){
            amax(suff[j], suff[j+1]);
        }

        rep(j,n+1){
            ll val = -inf2;
            if(j-1 >= 0){
                val = dp[u][j][0] + dp[v][j-1][1];
            }

            if(d-j >= j){
                dp[u][j][0] += suff[d-j];
                dp[u][j][1] += suff[d-j];
            }

            amax(dp[u][j][1], val);
        }
    }
}

void solve(int test_case)
{
    cin >> n >> d;
    amin(d,n+1);

    rep1(i,n-1){
        ll p; cin >> p;
        adj[p].pb(i);
    }

    dfs(0,-1);
    
    // rep(i,n){
    //     rep(j,n+1){
    //         cout << dp[i][j][1] << " ";
    //     }
    //     cout << endl;
    // }

    // cout << endl;

    ll ans = 0;

    rep(j,n+1){
        amax(ans,dp[0][j][1]);
    }

    cout << ans << endl;
}

int main()
{
    fastio;

    int t = 1;
    // cin >> t;

    rep1(i, t) {
        solve(i);
    }

    return 0;
}

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