Submission #898226

#	Time	Username	Problem	Language	Result	Execution time	Memory
898226		GrindMachine	Boarding Passes (BOI22_passes)	C++17	100 / 100	207 ms	27480 KiB

passes

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) (int)a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x,y) ((x+y-1)/(y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl

#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
#define rev(i,s,e) for(int i = s; i >= e; --i)
#define trav(i,a) for(auto &i : a)

template<typename T>
void amin(T &a, T b) {
    a = min(a,b);
}

template<typename T>
void amax(T &a, T b) {
    a = max(a,b);
}

#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif

/*



*/

const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;

vector<ll> add_pref[15][15], add_suff[15][15];

void solve(int test_case)
{
    string s; cin >> s;
    ll n = sz(s);
    s = "$" + s;

    ll siz = 0;
    rep1(i,n){
        amax(siz,(ll)s[i]-'A'+1);
    }

    vector<ll> pos[siz];
    rep1(i,n) pos[s[i]-'A'].pb(i);

    vector<ll> pref(n+5);

    rep(x,siz){
        fill(all(pref),0);
        trav(i,pos[x]){
            pref[i]++;
        }

        rep1(i,n) pref[i] += pref[i-1];
        
        rep(y,siz){
            if(x == y) conts;

            ll sum1 = 0, sum2 = 0;            
            add_pref[x][y].pb(0);
            add_suff[x][y].pb(0);

            trav(i,pos[y]){
                sum1 += pref[i];
                sum2 += pref[n]-pref[i];
                add_pref[x][y].pb(sum1);
                add_suff[x][y].pb(sum2);
            }
        }
    }

    vector<ll> dp(1<<siz,inf2);
    dp[0] = 0;

    rep(mask,1<<siz){
        vector<ll> seated;
        rep(c,siz){
            if(mask&(1<<c)){
                seated.pb(c);
            }
        }

        rep(c,siz){
            if(mask&(1<<c)) conts;

            ll sizp = sz(pos[c]);
            
            auto f = [&](ll i){
                ll s1 = i, s2 = sizp-i;
                ll cost1 = 0, cost2 = 0;
                trav(d,seated){
                    cost1 += add_pref[d][c][i];
                    cost2 += add_suff[d][c].back()-add_suff[d][c][i];
                }

                ll cost = s1*(s1-1)+s2*(s2-1)+cost1*4+cost2*4;
                return cost;
            };

            ll l = 0, r = sizp;
            ll p = sizp;

            while(l <= r){
                ll mid = (l+r) >> 1;
                if(f(mid) <= f(mid+1)){
                    p = mid;
                    r = mid-1;
                }
                else{
                    l = mid+1;
                }
            }

            ll mn_cost = inf2;

            for(int i = max(p-5,0ll); i <= min(p+5,sizp); ++i){
                amin(mn_cost,f(i));
            }

            amin(dp[mask|(1<<c)],dp[mask]+mn_cost);
        }
    }

    ld ans = (ld)dp[(1<<siz)-1]/4;
    cout << fixed << setprecision(11);
    cout << ans << endl;
}

int main()
{
    fastio;

    int t = 1;
    // cin >> t;

    rep1(i, t) {
        solve(i);
    }

    return 0;
}

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