Submission #742402

#	Time	Username	Problem	Language	Result	Execution time	Memory
742402		jamezzz	Tortoise (CEOI21_tortoise)	C++17	48 / 100	3093 ms	393168 KiB

tortoise

#include <bits/stdc++.h>
using namespace std;

#define sf scanf
#define pf printf
#define pb push_back
#define INF 1023456789

#define maxn 5005

int n,a[maxn],pv[maxn],nx[maxn];
vector<int> shop,play;
int memo[2*maxn][maxn][2];

int dp(int t,int i,int hv){
	if(i>=shop.size()||t>2*n)return 0;
	if(memo[t][i][hv]!=-1)return memo[t][i][hv];
	
	int sd=INF;
	if(pv[i]!=-1)sd=min(sd,shop[i]-play[pv[i]]);
	if(nx[i]<play.size())sd=min(sd,play[nx[i]]-shop[i]);
	
	int ans=0;
	
	//transition 0: don't do anything
	ans=max(ans,dp(t+shop[i+1]-shop[i],i+1,hv));
	
	for(int x=1;x<=a[shop[i]]+hv;++x){
		if(t+2*(x-1)*sd>2*shop[i])break;
		
		//transition 1: back and forth x times
		ans=max(ans,dp(t+2*x*sd+shop[i+1]-shop[i],i+1,0)+x);
		
		//transition 2: back and forth x-1 times, carry 1 to a playground in between i and i+1
		if(nx[i]<play.size()&&play[nx[i]]<shop[i+1]){
			ans=max(ans,dp(t+2*(x-1)*sd+shop[i+1]-shop[i],i+1,0)+x);
		}
		
		//transition 3: back and forth x-1 times, carry 1 to i+1, then let i+1 settle that
		ans=max(ans,dp(t+2*(x-1)*sd+shop[i+1]-shop[i],i+1,1)+x-1);
	}
	
	//pf("dp %d %d %d: %d\n",t,i,hv,ans);
	return memo[t][i][hv]=ans;
}

int main(){
	sf("%d",&n);
	int sm=0;
	for(int i=0;i<n;++i){
		sf("%d",&a[i]);
		if(a[i]==-1)play.pb(i);
		else shop.pb(i),sm+=a[i];
	}
	if(shop.size()==0){
		pf("0\n");
		return 0;
	}
	shop.pb(n);
	int cur=-1;
	for(int x=0;x<shop.size();++x){
		int i=shop[x];
		while(cur+1<play.size()&&play[cur+1]<i)++cur;
		pv[x]=cur;
		nx[x]=cur+1;
	}
	memset(memo,-1,sizeof memo);
	pf("%d\n",sm-dp(shop[0],0,0));
}

Compilation message (stderr)

tortoise.cpp: In function 'int dp(int, int, int)':
tortoise.cpp:16:6: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   16 |  if(i>=shop.size()||t>2*n)return 0;
      |     ~^~~~~~~~~~~~~
tortoise.cpp:21:10: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   21 |  if(nx[i]<play.size())sd=min(sd,play[nx[i]]-shop[i]);
      |     ~~~~~^~~~~~~~~~~~
tortoise.cpp:35:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   35 |   if(nx[i]<play.size()&&play[nx[i]]<shop[i+1]){
      |      ~~~~~^~~~~~~~~~~~
tortoise.cpp: In function 'int main()':
tortoise.cpp:61:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   61 |  for(int x=0;x<shop.size();++x){
      |              ~^~~~~~~~~~~~
tortoise.cpp:63:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   63 |   while(cur+1<play.size()&&play[cur+1]<i)++cur;
      |         ~~~~~^~~~~~~~~~~~
tortoise.cpp:48:4: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   48 |  sf("%d",&n);
      |    ^
tortoise.cpp:51:5: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   51 |   sf("%d",&a[i]);
      |     ^

• Subtask 1: 8 / 8
• Subtask 2: 10 / 10
• Subtask 3: 30 / 30
• Subtask 4: 0 / 25
• Subtask 5: 0 / 27