Submission #1058775

#	Time	Username	Problem	Language	Result	Execution time	Memory
1058775		gyg	Cat in a tree (BOI17_catinatree)	C++17	11 / 100	14 ms	9308 KiB

catinatree

#include <bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;
const int MAX_N = 1500 + 5, INF = 1e9;
 
int n, k;
array<vector<int>, MAX_N> adj;
 
array<array<int, MAX_N>, MAX_N> dist;
array<bool, MAX_N> seen;
void dfs(int u, int orig, int d = 0) {
    seen[u] = true, dist[orig][u] = d;
    for (int v : adj[u])
        if (!seen[v]) dfs(v, orig, d + 1);
}
void precomp() {
    for (int u = 1; u <= n; u++) {
        fill(seen.begin(), seen.end(), false);
        dfs(u, u);
    }
}
 
int query(int u) {
    int score = 0;
    for (int v = 1; v <= n; v++)
        score += (dist[u][v] < k);
    return score;
}
 
vector<pii> order;
array<bool, MAX_N> used;
int comp() {
    for (int u = 1; u <= n; u++) order.push_back({query(u), u});
    sort(order.begin(), order.end());    
    
    int ans = 0;
    for (pii x : order) {
        int u = x.second;
        if (used[u]) continue;
        ans++;
        for (int v = 1; v <= n; v++)
            if (dist[u][v] < k) used[v] = true;
    }
    return ans;
}
 
int main() {
    // freopen("cat.in", "r", stdin);
    cin >> n >> k; assert(n <= 1500);
    for (int u = 2; u <= n; u++) {
        int v; cin >> v; v++;
        adj[u].push_back(v), adj[v].push_back(u);
    }
 
    precomp();
    int ans = comp();
    cout << ans << '\n';
}

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