Submission #370314

#	Time	Username	Problem	Language	Result	Execution time	Memory
370314		ACmachine	Ball Machine (BOI13_ballmachine)	C++17	100 / 100	373 ms	33380 KiB

ballmachine

#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;

template<typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T, typename U> using ordered_map = tree<T, U, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

typedef long long ll;
typedef long double ld;

typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

typedef vector<int> vi;
typedef vector<ll> vll;

#define FOR(i,j,k,in) for(int i=(j); i < (k);i+=in)
#define FORD(i,j,k,in) for(int i=(j); i >=(k);i-=in)
#define REP(i,b) FOR(i,0,b,1)
#define REPD(i,b) FORD(i,b,0,1)
#define pb push_back 
#define mp make_pair
#define ff first
#define ss second
#define all(x) begin(x), end(x)
#define MANY_TESTS int tcase; cin >> tcase; while(tcase--)
	
const double EPS = 1e-9;
const int MOD = 1e9+7;
const ll INFF = 1e18;
const int INF = 1e9;
const ld PI = acos((ld)-1);
const vi dy = {1, 0, -1, 0, -1, 1, 1, -1};
const vi dx = {0, 1, 0, -1, -1, 1, -1, 1};

void DBG(){cout << "]" << endl;}
template<typename T, typename ...U> void DBG(const T& head, const U... args){ cout << head << "; "; DBG(args...); }
#define dbg(...) cout << "Line(" << __LINE__ << ") -> [" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__);
#define chk() cout << "Check at line(" << __LINE__ << ") hit." << endl;

template<class T, unsigned int U>
ostream& operator<<(ostream& out, const array<T, U> &v){out << "[";  REP(i, U) out << v[i] << ", ";  out << "]"; return out;}
template <class T, class U>
ostream& operator<<(ostream& out, const pair<T, U> &par) {out << "[" << par.first << ";" << par.second << "]"; return out;}
template <class T>
ostream& operator<<(ostream& out, const set<T> &cont) { out << "{"; for( const auto &x:cont) out << x << ", "; out << "}"; return out; }
template <class T, class U>
ostream& operator<<(ostream& out, const map<T, U> &cont) {out << "{"; for( const auto &x:cont) out << x << ", "; out << "}"; return out; }
template<class T>
ostream& operator<<(ostream& out, const vector<T> &v){ out << "[";  REP(i, v.size()) out << v[i] << ", ";  out << "]"; return out;}

template<class T>
istream& operator>>(istream& in, vector<T> &v){ for(auto &x : v) in >> x; return in; }
  
int main(){
 	ios_base::sync_with_stdio(false);
 	cin.tie(NULL); cout.tie(NULL);
    int n, q;
    cin >> n >> q;
    int root;
    vector<vector<int>> g(n);
    REP(i, n){
        int p; cin >> p;
        p--;
        if(p == -1)
            root = i;
        else{
            g[i].pb(p);
            g[p].pb(i);
        }
    }
    vector<int> subtree_minimum(n, INF);
    REP(i, n) subtree_minimum[i] = i;
    function<void(int, int)> gmin = [&](int v, int p){
        for(int x : g[v]){
            if(x == p) continue;
            gmin(x, v);
            subtree_minimum[v] = min(subtree_minimum[v], subtree_minimum[x]);
        }
    };
    gmin(root, -1);
    vector<int> order;
    vector<vector<int>> nxt(n, vector<int>(20, -1));
    function<void(int, int)> dfs = [&](int v, int p){
        auto cmp = [&](int lhs, int rhs){
            return subtree_minimum[lhs] < subtree_minimum[rhs];
        };
        sort(all(g[v]), cmp);
        nxt[v][0] = p; 
        FOR(i, 1, 20, 1){
            if(nxt[v][i - 1] != -1){
                nxt[v][i] = nxt[nxt[v][i - 1]][i - 1];
            }
        } 
        for(int x : g[v]){
            if(x == p) continue;
            dfs(x, v);
        }
        order.pb(v);
    };
    dfs(root, -1);
    vector<int> pos(n);
    REP(i, n) pos[order[i]] = i;
    set<int> free_positions;
    REP(i, n) free_positions.insert(i);
    vector<bool> isfree(n, true);
    auto insert_ball = [&](){
        int pos = *free_positions.begin();
        isfree[order[pos]] = false;
        free_positions.erase(free_positions.begin());
        return order[pos];
    };
    auto erase_ball = [&](int v){
        int x = v;
        int res = 0;
        REPD(i, 19){
            if(nxt[x][i] != -1 && !isfree[nxt[x][i]]){
                x = nxt[x][i];
                res += (1 << i);
            }
        }
        isfree[x] = true;
        free_positions.insert(pos[x]);
        return res;
    };
    REP(i, q){
        int type; cin >> type;
        if(type == 1){
            int k; cin >> k;
            int res;
            REP(j, k){
                res = insert_ball(); 
            }
            cout << res + 1 << "\n";
        }
        else{
            int x; cin >> x;
            x--;
            int res = erase_ball(x);
            cout << res << "\n";
        }
    }
    return 0;
}

Compilation message (stderr)

ballmachine.cpp: In function 'int main()':
ballmachine.cpp:136:32: warning: 'res' may be used uninitialized in this function [-Wmaybe-uninitialized]
  136 |             cout << res + 1 << "\n";
      |                                ^~~~
ballmachine.cpp:62:9: warning: 'root' may be used uninitialized in this function [-Wmaybe-uninitialized]
   62 |     int root;
      |         ^~~~

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