Submission #666931

#	Time	Username	Problem	Language	Result	Execution time	Memory
666931		Hacv16	Ball Machine (BOI13_ballmachine)	C++17	100 / 100	229 ms	127792 KiB

ballmachine

#include<bits/stdc++.h>
using namespace std;
     
typedef long long ll;
     
const int MAX = 1e6 + 10;
const int LOG = 22;
const int INF = 0x3f3f3f3f;
     
int n, q, filled[MAX], root, t, order[MAX], dp[MAX][LOG], d[MAX], mn[MAX];
vector<int> adj[MAX];
set<pair<int, int>> s;
       
bool cmp(int u, int v){ return mn[u] < mn[v]; }

void dfs(int u, int p, int dist){
    d[u] = dist, mn[u] = u;
     
    for(auto v : adj[u]){
        if(v == p) continue;
        dfs(v, u, dist + 1);
        mn[u] = min(mn[u], mn[v]);
    }

    sort(adj[u].begin(), adj[u].end(), cmp);
}

void dfs2(int u, int p){
    for(auto v : adj[u]){
        if(v == p) continue;
        dfs2(v, u);
    }
     
    order[u] = ++t;
    s.insert({order[u], u});
}
     
int query(ll u){
    int old = d[u];
     
    for(int i = LOG - 1; i >= 0; i--){
        int j = dp[u][i];
        if(j == -1) continue;
        if(filled[j]) u = j;
    }

    s.insert({order[u], u});
    filled[u] = false;
     
    return old - d[u];
}

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
     
    cin >> n >> q;
     
    memset(dp, -1, sizeof(dp));
     
    for(int i = 1; i <= n; i++){
        int x; cin >> x;
     
        if(x != 0){
            adj[x].push_back(i);
            adj[i].push_back(x);
            dp[i][0] = x;
     
        }else{ root = i; }
    }
     
    dfs(root, -1, 0);
    dfs2(root, -1);
     
    for(int j = 1; j < LOG; j++){
        for(int i = 1; i <= n; i++){
            if(dp[i][j - 1] == -1) continue;
            dp[i][j] = dp[dp[i][j - 1]][j - 1];
        }
    }
     
    while(q--){
        int op, k; cin >> op >> k;
     
        if(op == 1){
            int last = -1;
     
            while(k-- && s.size()){
                int cur = (*(s.begin())).second;
                filled[cur] = true;
                last = cur;
     
                s.erase(s.begin());
            }
     
            cout << last << '\n';
     
        }else{
            cout << query(k) << '\n';
        }
    }
     
    return 0;
}

• Subtask 1: 25 / 25
• Subtask 2: 30 / 30
• Subtask 3: 40 / 40
• Subtask 4: 5 / 5