Submission #959427

#	Time	Username	Problem	Language	Result	Execution time	Memory
959427		thunopro	Ball Machine (BOI13_ballmachine)	C++14	100 / 100	313 ms	38264 KiB

ballmachine

#include<bits/stdc++.h>
using namespace std ; 
#define maxn 200009 
#define ll long long 
#define fi first 
#define se second 
#define pb push_back 
#define left id<<1
#define right id<<1|1 
#define _lower(x) lower_bound(v.begin(),v.end(),x)-v.begin()+1 
#define TIME (1.0*clock()/TIME_PERS_SEC) 
#define re exit(0); 

const int mod = 1e9+7 ; 
const int INF = 1e9 ; 
const int LOG = 18 ; 

typedef vector<int> vi ; 
typedef pair<int,int> pii ; 
typedef vector<pii> vii ; 

void add ( int &a , int b ) 
{
	a += b ; 
	if ( a >= mod ) a -= mod ; 
	if ( a < 0 ) a += mod ; 
}

template < typename T > void chkmin ( T &a , T b ) { if ( a > b ) a = b ;} 
template < typename T > void chkmax ( T &a , T b ) { if ( a < b ) a = b ;} 

void rf () 
{
	freopen ("bai1.inp","r",stdin) ; 
}

mt19937 rng (time(0)) ; 

int _pow ( int a , int n ) 
{
	if ( n == 0 ) return 1 ; 
	int res = _pow (a,n/2) ; 
	if ( n % 2 ) return 1ll*res*res%mod*a%mod ; 
	else return 1ll*res*res%mod ; 
}

int n , nq , root ; 
vi adjList [maxn] ; 
vi child [maxn] ; 

int dp [maxn] ;
int par [maxn][20] , dep [maxn] ; 
void dfs ( int u ) 
{
	dp [u] = u ; 
	for ( auto v : adjList [u] ) 
	{
		if ( v == par [u][0] ) continue ; 
		par [v][0] = u ; dep [v] = dep [u] + 1 ; 
		for ( int i = 1 ; i <= LOG ; i ++ ) par [v][i] = par[par[v][i-1]][i-1] ; 
		dfs (v) ; 
		chkmin (dp[u],dp[v]) ; 
		child [u] . pb (v) ; 
	}
}

bool cmp ( int u , int v ) 
{
	return dp [u] < dp [v] ; 
}

int ver1 [maxn] , ver2 [maxn] ; 
void find_order ( int u ) 
{
	static int cnt = 0 ; 
	for ( auto v : child [u] ) find_order (v) ; 
	ver1 [++cnt] = u ; 
	ver2 [u] = cnt ; 
} 

int have_ball [maxn] ; 
int T [maxn*4] ; 
void update ( int id , int l , int r , int pos , int w ) 
{
	if ( l > pos || r < pos ) return ; 
	if ( l == r ) 
	{
		T [id] = w ; 
		return ; 
	}
	int mid = (l+r)/2 ; 
	update (left,l,mid,pos,w) ; 
	update (right,mid+1,r,pos,w) ; 
	T [id] = min (T[left],T[right]) ; 
}
int get ( int id , int l , int r ) 
{
	if ( l == r ) return l ; 
	int mid = (l+r)/2 ; 
	if ( T [left] == 0 ) return get (left,l,mid) ; 
	else return get (right,mid+1,r) ; 
}

int jump ( int x , int h ) 
{
	for ( int i = LOG ; i >= 0 ; i -- ) if ( h >> i & 1 ) x = par [x][i] ; 
	return x ; 
}
int main ()
{
	ios_base::sync_with_stdio(0); 
	cin.tie(0);cout.tie(0); 
//	rf () ; 
	cin >> n >> nq ; 
	for ( int i = 1 ; i <= n ; i ++ ) 
	{
		int x ; cin >> x ; 
		if ( x == 0 ) root = i ; 
		else 
		{
			adjList [x] . pb (i) ; 
			adjList [i] . pb (x) ; 
		}
	}
	
	dfs (root) ; 
	
	for ( int i = 1 ; i <= n ; i ++ ) sort (child[i].begin(),child[i].end(),cmp) ; 
	
	find_order (root) ; 
	
	while ( nq -- ) 
	{
		int op , x ; cin >> op >> x ; 
		if ( op == 1 ) 
		{
			int pos ; 
			while ( x -- ) 
			{
				pos = get (1,1,n) ; 
				update (1,1,n,pos,1) ;
				have_ball [ver1[pos]] = 1 ;  
			}
			cout << ver1[pos] << "\n" ;
		}
		else 
		{
			int l = 0 , r = dep [x] , res; 
			while ( l <= r ) 
			{
				int mid = (l+r)/2 ; 
				int parent = jump (x,mid) ; 
				if ( have_ball [parent] == true ) l = mid+1 , res = mid ; 
				else r = mid-1 ;
			}
			int parent = jump (x,res) ;  
			have_ball [parent] = 0 ; 
			update (1,1,n,ver2[parent],0) ; 
			cout << res << "\n" ; 
		}
	}
}

Compilation message (stderr)

ballmachine.cpp: In function 'void rf()':
ballmachine.cpp:34:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   34 |  freopen ("bai1.inp","r",stdin) ;
      |  ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
ballmachine.cpp: In function 'int main()':
ballmachine.cpp:106:45: warning: 'res' may be used uninitialized in this function [-Wmaybe-uninitialized]
  106 |  for ( int i = LOG ; i >= 0 ; i -- ) if ( h >> i & 1 ) x = par [x][i] ;
      |                                           ~~^~~~
ballmachine.cpp:148:30: note: 'res' was declared here
  148 |    int l = 0 , r = dep [x] , res;
      |                              ^~~
ballmachine.cpp:144:25: warning: 'pos' may be used uninitialized in this function [-Wmaybe-uninitialized]
  144 |    cout << ver1[pos] << "\n" ;
      |                         ^~~~

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