Submission #409996

#	Time	Username	Problem	Language	Result	Execution time	Memory
409996		CaroLinda	The short shank; Redemption (BOI21_prison)	C++14	55 / 100	1974 ms	176228 KiB

prison

#include <bits/stdc++.h>

#define sz(x) (int)(x.size())
#define all(x) x.begin(),x.end()

const int MAXN = 4010 ;
const int MAX = 2e6+10 ;
const int MAX4 = 150004 ;

using namespace std ;

int N , D , T , toGet, toFill = 1 ;
int t[MAX] ;
int dp[2][MAX]; 
int cost[MAXN][MAXN] ;

void solve(int l, int r, int optmin , int optmax )
{
	if(l > r) return ;

	int mid = (l+r)>>1 ;
	int opt = optmin ;
	dp[toFill][mid] = cost[opt][mid]+dp[toGet][opt-1] ;

	for(int i = optmin+1 ; i <= min(mid,optmax) ; i++ )
	{
		int newCost = cost[i][mid] + dp[toGet][i-1] ;
		if(newCost >= dp[toFill][mid]) continue ;
		opt = i ;
		dp[toFill][mid] = newCost ;
	}

	solve(l, mid-1, optmin, opt ) ;
	solve(mid+1, r, opt, optmax  );
}

void solve2()
{

	vector<int> dpSuf(N+2,0) ;
	vector<int> r(N+1,N+1) ;

	for(int i = N ; i > 0 ; i-- )
	{
		r[i] = i+1 ;

		while( r[i] <= N && t[i]+r[i]-i < t[r[i]] ) r[i] = r[ r[i] ] ;

		int k = T-t[i]+i ;

		dpSuf[i] = dpSuf[r[i]]+max(0,min( r[i]-1 , k )-i+1 ) ;
	}

	int s = t[1]+1 ;
	int qtd = t[1] <= T ;

	int ans = qtd+dpSuf[2] ;

	for(int i = 2 ; i <= N ; i++ , s++ )
	{
		s = min(s, t[i] ) ;
		qtd += s <= T ;

		ans = min(ans, qtd+dpSuf[i+1]) ;
	}

	printf("%d\n" , ans ) ;

	exit(0) ;
}

vector<int> p ;
int K ;
int tree[MAX4*4] ;
int lz[MAX4*4] ;

int m(int l, int r) { return (l+r)>>1 ; }

void refresh(int pos, int l, int r)
{
	tree[pos] += lz[pos] ;
	tree[pos] = min(tree[pos] , N+5) ;

	if(l == r) return (void)(lz[pos] = 0 ) ;

	lz[pos<<1] += lz[pos] ;
	lz[pos<<1|1] += lz[pos] ;

	lz[pos] = 0 ;

}

void clean(int pos, int l, int r, int beg, int en )
{
	refresh(pos,l,r) ;

	if(tree[pos] == N+5 || l > en || r < beg ) return ;
	if( l== r )
	{
		tree[pos] = N+5 ;
		return ;
	}

	clean(pos<<1 , l , m(l,r) , beg, en ) ;
	clean(pos<<1|1 , m(l,r)+1, r , beg, en ) ;

	tree[pos] = min(tree[pos<<1] , tree[pos<<1|1]) ; 
}
void getMin(int pos, int l, int r, int beg, int en, int &cur )
{
	refresh(pos,l,r) ;

	if( l > en || r < beg) return ;
	if( l >= beg && r <= en ) return (void)( cur = min(cur,tree[pos]) ) ;

	getMin(pos<<1 , l , m(l,r ) , beg, en , cur ) ;
	getMin(pos<<1|1 , m(l,r)+1, r, beg, en, cur ) ;

}

void updPoint(int pos, int l , int r, int x, int val )
{
	refresh(pos,l,r) ;
	tree[pos] = min(tree[pos] , val ) ;

	if( l == r ) return ;
	if( x <= m(l,r) ) updPoint(pos<<1 , l , m(l,r) , x , val ) ;
	else updPoint(pos<<1|1 , m(l,r)+1 , r, x, val ) ;

}

void updInterval(int pos , int l, int r, int beg, int en ) 
{
	refresh(pos,l,r) ;

	if(l > en || r < beg) return ;
	if( l >= beg && r <= en )
	{
		lz[pos]++ ;
		refresh(pos,l,r) ;
		return ;
	}

	updInterval(pos<<1 , l , m(l,r) , beg, en ) ;
	updInterval(pos<<1|1 , m(l,r)+1, r, beg, en ) ;

	tree[pos] = min(tree[pos<<1] , tree[pos<<1|1]) ;

}

void solve4()
{
	for(int i = 1 ; i <= N ; i++ )
	{
		p.push_back( t[i]-i ) ;
		p.push_back( T-i ) ;
	}
	sort(all(p)) ;
	p.erase(unique(all(p)) , p.end() ) ;

	K = sz(p) ;

	int s = T+1 ;

	for(int i = 1 ; i <= N ; i++ , s++ )
	{
		s = min(s, t[i]) ;
		dp[0][i] = dp[0][i-1]+(s <= T) ;
	}

	for(int j = 1 ; j <= D ; j++ , swap(toGet, toFill) )
	{

		clean(1,0,K-1, 0, K-1 ) ;

		for(int i = 1 ; i <= N ; i++ ) 
		{
			int a = lower_bound(all(p), t[i]-i ) - p.begin() ;
			int b = lower_bound(all(p), T-i ) - p.begin() ;
			int cur = dp[toGet][i-1] ;

			getMin( 1 , 0 , K-1 , a , K-1 , cur ) ;
			clean(1,0,K-1, a, K-1) ;
			updPoint(1,0,K-1, a, cur ) ;
			updInterval(1,0,K-1, 0, b ) ;

			dp[toFill][i] = N+5 ;

			getMin(1,0,K-1, 0, K-1 , dp[toFill][i]) ;
		}

	}

	printf("%d\n" , dp[toGet][N] ) ;

	exit(0) ;

}

int main()
{
	scanf("%d %d %d", &N, &D, &T  ) ;
	for(int i = 1 ; i <= N ; i++ ) scanf("%d", &t[i] ) ;

	if( D <= 1 ) solve2() ;
	if( D <= 15 ) solve4() ;

	for(int i = 1 ; i <= N ; i++ )
	{
		int s = t[i]+1 ;
		cost[i][i] = t[i] <= T ;

		for(int j = i+1 ; j <= N ; j++ , s++ )
		{
			s = min(s, t[j] ) ;
			cost[i][j] = cost[i][j-1]+(s <= T ) ;
		}

	}

	for(int i = 1 ; i <= N ; i++ ) dp[0][i] = cost[1][i] ;
	for(int i = 1 ; i <= D ; i++ , swap(toGet, toFill) ) 
	{
		for(int j = 1 ; j <= i ; j++ ) dp[toFill][j] = dp[toGet][j] ;
		solve(i+1, N, i+1, N ) ;
	}

	printf("%d\n", dp[toGet][N] ) ;

}		

Compilation message (stderr)

prison.cpp: In function 'int main()':
prison.cpp:202:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  202 |  scanf("%d %d %d", &N, &D, &T  ) ;
      |  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
prison.cpp:203:38: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  203 |  for(int i = 1 ; i <= N ; i++ ) scanf("%d", &t[i] ) ;
      |                                 ~~~~~^~~~~~~~~~~~~~

• Subtask 1: 15 / 15
• Subtask 2: 10 / 10
• Subtask 3: 20 / 20
• Subtask 4: 10 / 10
• Subtask 5: 0 / 25
• Subtask 6: 0 / 20