Submission #1176716

#	Time	Username	Problem	Language	Result	Execution time	Memory
1176716		Zbyszek99	Boarding Passes (BOI22_passes)	C++20	100 / 100	270 ms	52228 KiB

passes

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ll long long
#define ld long double
#define ull unsigned long long
#define ff first
#define ss second
#define pii pair<int,int>
#define pll pair<long long, long long>
#define vi vector<int>
#define vl vector<long long>
#define pb push_back
#define rep(i, b) for(int i = 0; i < (b); ++i)
#define rep2(i,a,b) for(int i = a; i <= (b); ++i)
#define rep3(i,a,b,c) for(int i = a; i <= (b); i+=c)
#define count_bits(x) __builtin_popcountll((x))
#define all(x) (x).begin(),(x).end()
#define siz(x) (int)(x).size()
#define forall(it,x) for(auto& it:(x))
using namespace __gnu_pbds;
using namespace std;
typedef tree<int, null_type, less<int>, rb_tree_tag,tree_order_statistics_node_update> ordered_set;
//mt19937 mt;void random_start(){mt.seed(chrono::time_point_cast<chrono::milliseconds>(chrono::high_resolution_clock::now()).time_since_epoch().count());}
//ll los(ll a, ll b) {return a + (mt() % (b-a+1));}
const int INF = 1e9+50;
const ll INF_L = 1e18+40;
const ll MOD = 1e9+7;

ll dp_add[15][(1 << 15)];
ll L_pref[15][100'001];
ll R_pref[15][100'001];
ll L_val[15][100'001];
ll R_val[15][100'001];
ll dp[(1 << 15)];
vi ind[15];

int main()
{
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    //random_start();
    string s;
    cin >> s;
    int n = siz(s);
    rep(i,n)
    {
        ind[s[i] - 'A'].pb(i);
    }
    rep(i,15)
    {
        rep(j,15)
        {
            //L
            int p2 = 0;
            ll cur_sum = 0;
            ll cur_add = 0;
            rep(p1,siz(ind[i]))
            {
                while(p2 < siz(ind[j]) && ind[j][p2] < ind[i][p1])
                {
                    cur_add++;
                    p2++;
                }
                cur_sum += cur_add;
                L_pref[j][p1] = cur_sum;
                L_val[j][p1] = cur_add;
            }
            //R
            p2 = siz(ind[j])-1;
            cur_sum = 0;
            cur_add = 0;
            for(int p1 = siz(ind[i])-1; p1 >= 0; p1--)
            {
                while(p2 >= 0 && ind[j][p2] > ind[i][p1])
                {
                    cur_add++;
                    p2--;
                }
                cur_sum += cur_add;
                R_pref[j][p1] = cur_sum;
                R_val[j][p1] = cur_add;
            }
        }
        rep(mask,(1 << 15))
        {
            int l = 0;
            int r = siz(ind[i])-1;
            ll ans = -1;
            while(l <= r)
            {
                int mid = (l+r)/2;
                ll L_sum = 0;
                ll R_sum = 0;
                rep(j,15)
                {
                    if(mask & (1 << j))
                    {
                        L_sum += L_val[j][mid];
                        R_sum += R_val[j][mid];
                    }
                }
                if(L_sum * 2 + mid <= R_sum * 2 + (siz(ind[i])-mid-1))
                {
                    ans = mid;
                    l = mid+1;
                }
                else
                {
                    r = mid-1;
                }
            }
            ll Ls = 0;
            ll Rs = 0;
            rep(j,15)
            {
                if(mask & (1 << j))
                {
                    if(ans != -1) Ls += L_pref[j][ans]*2;
                    if(ans != siz(ind[i])-1) Rs += R_pref[j][ans+1]*2;
                }
            }
            
            dp_add[i][mask] = (ans != -1 ? Ls + ((ans+1) * ans) / 2 : 0) + (ans != siz(ind[i])-1 ? Rs + ((ll)(siz(ind[i])-ans-2 + 1) * (ll)(siz(ind[i])-ans-2))/2 : 0);
        }
    }
    dp[0] = 0;
    rep2(mask,1,(1 << 15)-1)
    {
        ll ans = 1e18;
        rep(i,15)
        {
            if(mask & (1 << i))
            {
                ans = min(ans,dp[mask-(1 << i)] + dp_add[i][mask-(1 << i)]);
            }
        }
        dp[mask] = ans;
    }
    cout << dp[(1 << 15)-1]/2;
    if(dp[(1 << 15)-1] % 2 == 1) cout << ".5\n";
}

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