Submission #624261

#	Time	Username	Problem	Language	Result	Execution time	Memory
624261		jeroenodb	Cat in a tree (BOI17_catinatree)	C++14	100 / 100	71 ms	21120 KiB

catinatree

#include "bits/stdc++.h"
using namespace std;
#define all(x) begin(x),end(x)
template<typename A, typename B> ostream& operator<<(ostream &os, const pair<A, B> &p) { return os << '(' << p.first << ", " << p.second << ')'; }
template<typename T_container, typename T = typename enable_if<!is_same<T_container, string>::value, typename T_container::value_type>::type> ostream& operator<<(ostream &os, const T_container &v) { string sep; for (const T &x : v) os << sep << x, sep = " "; return os; }
#define debug(a) cerr << "(" << #a << ": " << a << ")\n";
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int,int> pi;
const int mxN = 2e5+3, oo = 1e9;
int choice[mxN],d[mxN],N,D, minput[mxN];
vi adj[mxN], ans;
void dfs(int at, int from) {
    choice[at]=at;
    minput[at]=oo;
    for(int to : adj[at]) if(to!=from) {
        d[to] = d[at]+1;
        dfs(to,at);
        minput[at] = min(minput[at],minput[to]+1);
        if(choice[to]) {
            if((d[choice[to]]-d[at])*2>=D) {
                ans.push_back(choice[to]);
                minput[at] = min(minput[at], d[choice[to]]-d[at]);
            } else if(d[choice[to]]>d[choice[at]]) {
                choice[at] = choice[to];
            }
        }
    }
    int got = d[choice[at]]-d[at];
    if(got+minput[at]<D) {
        choice[at]=0;
    }
}
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cin >> N >> D;
    for(int i=2;i<=N;++i) {
        int x; cin >> x;
        adj[x+1].push_back(i);
    }
    dfs(1,0);
    if(choice[1]) ans.push_back(choice[1]);
    cout << ans.size() << '\n'; //<< ans << '\n';

}

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