Submission #652272

#	Time	Username	Problem	Language	Result	Execution time	Memory
652272		inksamurai	Boarding Passes (BOI22_passes)	C++17	60 / 100	2073 ms	5168 KiB

passes

#include <bits/stdc++.h>
#define int ll
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define rng(i,c,n) for(int i=c;i<n;i++)
#define fi first
#define se second
#define pb push_back
#define sz(a) (int)a.size()
#define vec(...) vector<__VA_ARGS__>
#define _3CZAtRo ios::sync_with_stdio(0),cin.tie(0)
typedef long long ll;
using pii=pair<int,int>;
using vi=vector<int>;
void print(){cout<<'\n';}
template<class h,class...t>
void print(const h&v,const t&...u){cout<<v<<' ',print(u...);}

void chmin(int&a,const int&b){
	a=min(a,b);
}

signed main(){
_3CZAtRo;
	int n;
	vi a;
	{
		string s;
		cin>>s;
		n=sz(s);
		vi tmp;
		rep(i,n){
			tmp.pb(s[i]-'A');
		}
		sort(tmp.begin(),tmp.end());
		tmp.erase(unique(tmp.begin(),tmp.end()),tmp.end());
		rep(i,n){
			int v=lower_bound(tmp.begin(),tmp.end(),s[i]-'A')-tmp.begin();
			a.pb(v);
		}
	}
	// rep(i,n){
	// 	cout<<a[i]<<" ";
	// }
	// print();
	int si=sz(set<int>(a.begin(),a.end()));
	vec(vi) rbts(si);
	rep(i,n){
		rbts[a[i]].pb(i);
	}
	const int inf=1e15;
	vi dp(1<<si,inf);
	dp[0]=0;
	rep(msk,1<<si){
		vi usd(n);
		rep(v,si){
			if(msk>>v&1){
				for(auto j:rbts[v]){
					usd[j]=1;
				}
			}
		}
		int now=dp[msk];
		rep(v,si){
			if(!(msk>>v&1)){
				int nmsk=msk|(1<<v);
				for(auto j:rbts[v]){
					usd[j]=2;
				}
				int w=inf;
				{
					vi pf(n);
					int cnt1=0,cnt2=0;
					rep(i,n){
						if(i){
							pf[i]+=pf[i-1];
						}
						if(usd[i]==2){
							pf[i]+=cnt2;
							pf[i]+=cnt1*2;
							cnt2+=1;
						}else if(usd[i]==1){
							cnt1+=1;
						}
					}
					vi sf(n);
					cnt1=0,cnt2=0;
					per(i,n){
						if(i<n-1){
							sf[i]+=sf[i+1];
						}
						if(usd[i]==2){
							sf[i]+=cnt2;
							sf[i]+=cnt1*2;
							cnt2+=1;
						}else if(usd[i]==1){
							cnt1+=1;
						}
					}
					w=min(sf[0],pf[n-1]);
					rep(i,n-1){
						w=min(w,pf[i]+sf[i+1]);
					}
					// if(msk==0 and v==1){
					// 	rep(i,n){
					// 		cout<<pf[i]<<" ";
					// 	}	
					// 	print();
					// }
				}
				chmin(dp[nmsk],w+now);
				for(auto j:rbts[v]){
					usd[j]=0;
				}
			}
		}
	}
	int ans=dp[(1<<si)-1];
	cout<<ans/2<<(ans%2?".5":"")<<"\n";
}

• Subtask 1: 5 / 5
• Subtask 2: 25 / 25
• Subtask 3: 30 / 30
• Subtask 4: 0 / 40