Submission #1106931

#	Time	Username	Problem	Language	Result	Execution time	Memory
1106931		Ali_BBN	Cat in a tree (BOI17_catinatree)	C++14	100 / 100	377 ms	447172 KiB

catinatree

#include <bits/stdc++.h>
#define mp make_pair
#define ll long long
#define migmig cin.tie(NULL);ios_base::sync_with_stdio(false)
#define max_heap(T) priority_queue<T>
#define min_heap(T) priority_queue<T, vector<T>, greater<T>>
#define pb push_back
#define fi first
#define sec second
#define endl "\n"
#define pii pair <int, int>
using namespace std;
const ll MOD = 1e9 + 7;
const int INF = 1e9 + 1;
const ll INF18 = 1e18 + 1;
const int MAXN = 2e5 + 1;
const int LOG = 23;
int dp[MAXN][300];
vector <int> adj[MAXN];
int h[MAXN];
int maax, maxy;
int par[MAXN];
bool visited[MAXN];
int d;
int dp2[MAXN][300];
int be[MAXN];
void dfs(int r){
    for (int i : adj[r]){
        if (par[r] == i) continue;
        dfs(i);
        for (int j = 1; j <= d; j++) dp2[r][j] += dp[i][j - 1];
    }
    for (int i : adj[r]){
        if (par[r] == i) continue;
        for (int j = 1; j <= d / 2; j++){
            dp[r][j] = max(dp[r][j], dp2[r][d - j] - dp[i][d - j - 1] + dp[i][j - 1]);
        }
    }
    for (int j = d / 2 + 1; j <= d; j++) dp[r][j] = dp2[r][j];
    dp[r][0] = dp2[r][d] + 1;
    for (int j = d - 1; j >= 0; j--) dp[r][j] = max(dp[r][j], dp[r][j + 1]);
}
void dfs2(int r){
    visited[r] = 1;
    if (be[r] && h[r] > maax) maax = h[r], maxy = r;
    for (int i : adj[r]){
        if (visited[i] == 1) continue;
        h[i] = h[r] + 1;
        dfs2(i);
    }
}
void solve(){
    int n;
    cin >> n >> d;
    for (int i = 1; i < n; i++){
        int u;
        cin >> u;
        par[i] = u;
        adj[u].pb(i);
        adj[i].pb(u);
    }
    d = min(n, d);
    if (d < 300){
        dfs(0);
        cout << dp[0][0] << endl;
    }
    else{
        int num = 0;
        int v = 0;
        for (int i = 0; i < n; i++) be[i] = 1;
        while(1){
            h[v] = 0, maax = -1;
            memset(visited, 0, sizeof(visited));
            dfs2(v);
            int u = maxy;
            h[u] = 0, maax = -1;
            memset(visited, 0, sizeof(visited));
            dfs2(u);
            num++;
            for (int i = 0; i < n; i++){
                if (be[i] && h[i] < d){
                    be[i] = 0;
                    if (v == i) v = -1;
                }
                else if (be[i] && v == -1) v = i;
            }
            if (v == -1) break;
        }
        cout << num << endl;
    }
}
int main(){
	migmig;
	int tc = 1;
	// cin >> tc;
	for (int ti = 0; ti < tc; ti++) solve();
}

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