Submission #1106023

#	Time	Username	Problem	Language	Result	Execution time	Memory
1106023		monaxia	Ball Machine (BOI13_ballmachine)	C++17	100 / 100	161 ms	33736 KiB

ballmachine

// credit: Mai Hong Kien
 
#include <bits/stdc++.h>
#define pb push_back
#define ppb pop_back
#define fr first
#define sc second
#define all(v) v.begin(), v.end()
#define mod (long long)(1e9 + 7)
#define eps (long long)(1e-9)
using namespace std;
 
using ll = long long;
using ull = unsigned long long;
using ld = long double;
ll LIMIT = 2e3 + 5;
 
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
ll random (ll l, ll r){return uniform_int_distribution <ll> (l, r)(rng);}

const ll Mod = 1e9 + 7;

vector <int> min_index(1e5 + 1), euler;
vector <vector <int>> p(1e5 + 1, vector <int> (30, -1));

void init(int n){
    for(int j = 1; (1 << j) < n; j ++){
        for(int i = 1; i <= n; i ++){
            if(p[i][j - 1] != -1) p[i][j] = p[p[i][j - 1]][j - 1];
        }
    }
}

bool comp(int& a, int& b){
    return min_index[a] > min_index[b];
}

void init_min(int node, vector <vector <int>>& graph, vector <int>& min_index){
    for(auto& x : graph[node]){
        init_min(x, graph, min_index);
        min_index[node] = min(min_index[node], min_index[x]);
    }
}

void dfs_euler(int node, vector <vector <int>>& graph){
    euler.pb(node);

    for(auto& x : graph[node]) dfs_euler(x, graph);
}

void solve(){
    int n, q, start = 1, cnt = 0;
    cin >> n >> q;

    vector <vector <int>> graph(n + 1);
    vector <int> id(n + 1), ball(n + 1, 0);

    for(int i = 1; i <= n; i ++){
        cin >> p[i][0];
        if(p[i][0]) graph[p[i][0]].pb(i); 
        else start = i;
    }

    init(n);

    for(int i = 1; i <= n; i ++) min_index[i] = i;

    init_min(start, graph, min_index);

    for(int i = 1; i <= n; i ++) sort(all(graph[i]), comp);

    dfs_euler(start, graph);
    reverse(all(euler));

    set <pair <int, int>> s;

    for(int i = 0; i < euler.size(); i ++) s.insert({i + 1, euler[i]}), id[euler[i]] = i + 1;

    while(q --){
        int type, x;
        cin >> type >> x;

        if(type == 1){
            while(x --){
                auto it = s.begin();
                ball[it -> sc] = 1;

                if(!x) cout << it -> sc << "\n";

                s.erase(it);
            }

            continue;
        }

        if(type == 2){
            int ans = 0;

            int op_cnt = 0;

            while(ball[p[x][0]]){
                int i = __lg(n), cur = 1 << __lg(n);

                while(p[x][i] == -1 || !ball[p[x][i]]) i --, cur >>= 1;

                x = p[x][i];
                ans += cur;
            }

            s.insert({id[x], x});

            ball[x] = 0;

            cout << ans << "\n";
        }
    }
} 

 
signed main()
{
    cin.tie(0)->sync_with_stdio(0);
 
    if(fopen("TOY.inp", "r")){
        freopen("TOY.inp", "r", stdin);
        freopen("TOY.out", "w", stdout);
    }
    
    // cout << 1; return 0;
 
    ll n = 1;
 
    // cin >> n;

    while(n) {
        solve();
        n --;
        cout << "\n";
    }
 
    // cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
}

Compilation message (stderr)

ballmachine.cpp: In function 'void solve()':
ballmachine.cpp:77:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   77 |     for(int i = 0; i < euler.size(); i ++) s.insert({i + 1, euler[i]}), id[euler[i]] = i + 1;
      |                    ~~^~~~~~~~~~~~~~
ballmachine.cpp:99:17: warning: unused variable 'op_cnt' [-Wunused-variable]
   99 |             int op_cnt = 0;
      |                 ^~~~~~
ballmachine.cpp:52:26: warning: unused variable 'cnt' [-Wunused-variable]
   52 |     int n, q, start = 1, cnt = 0;
      |                          ^~~
ballmachine.cpp: In function 'int main()':
ballmachine.cpp:125:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  125 |         freopen("TOY.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
ballmachine.cpp:126:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  126 |         freopen("TOY.out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

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