Submission #668208

#	Time	Username	Problem	Language	Result	Execution time	Memory
668208		fatemetmhr	Boarding Passes (BOI22_passes)	C++17	100 / 100	217 ms	48344 KiB

passes

// Willkommen! hier ist der Ort, an dem du sterben wirst :)

#include <bits/stdc++.h>

using namespace std;

typedef long long   ll;
typedef long double ld;

#define all(x) x.begin(), x.end()
#define pb     push_back
#define fi     first
#define se     second

const int maxn5 = 1e5 + 10;
const ll  inf   = 1e18;
const int lg    = 30;
const int al    = 15; /// REMEMBER YOU'VE CHANGED THISSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS

vector <int> av[al + 2];
ll lef[al + 1][maxn5], rig[al + 1][maxn5];
ll pslef[al + 1][maxn5], psrig[al + 1][maxn5];
ll dp[1 << al];

inline bool check(int id, int lim, int mask){
    ll val = 2 * lim - int(av[id].size()) + 1;
    for(int i = 0; i < al; i++) if((mask >> i)&1)
        val += 2 * (lef[i][av[id][lim]] - rig[i][av[id][lim]]);
    return val <= 0;
}

int main(){
    ios_base::sync_with_stdio(false); cin.tie(0);

    string s; cin >> s;
    int n = s.size();

    for(int i = 0; i < n; i++)
        av[s[i] - 'A'].pb(i);

    lef[s[0] - 'A'][0] = 1;
    for(int i = 1; i < n; i++){
        for(int j = 0; j < al; j++){
            lef[j][i] = lef[j][i - 1] + (s[i] - 'A' == j);
        }
    }

    rig[s[n - 1] - 'A'][n - 1] = 1;
    for(int i = n - 2; i >= 0; i--){
        for(int j = 0; j < al; j++){
            rig[j][i] = rig[j][i + 1] + (s[i] - 'A' == j);
        }
    }

    for(int i = 0; i < al; i++) if(av[i].size()){
        for(int j = 0; j < al; j++)
            pslef[j][av[i][0]] = lef[j][av[i][0]];
        for(int j = 1; j < av[i].size(); j++) for(int k = 0; k < al; k++)
            pslef[k][av[i][j]] = pslef[k][av[i][j - 1]] + lef[k][av[i][j]];
        reverse(all(av[i]));
        for(int j = 0; j < al; j++)
            psrig[j][av[i][0]] = rig[j][av[i][0]];
        for(int j = 1; j < av[i].size(); j++) for(int k = 0; k < al; k++)
            psrig[k][av[i][j]] = psrig[k][av[i][j - 1]] + rig[k][av[i][j]];
        reverse(all(av[i]));
    }

    for(int mask = 1; mask < (1 << al); mask++){
        dp[mask] = inf;
        for(int i = 0; i < al; i++) if((mask >> i)&1){
            if(av[i].empty()){
                dp[mask] = dp[mask ^ (1 << i)];
                break;
            }
            ll lo = -1, hi = av[i].size();
            while(hi - lo > 1){
                int mid = (lo + hi) >> 1;
                if(check(i, mid, mask ^ (1 << i)))
                    lo = mid;
                else
                    hi = mid;
            }
            ll len = av[i].size();
            ll val = hi * (hi - 1) + (len - hi) * (len - hi - 1);
            //cout << val << endl;
            if(lo > -1){
                for(int j = 0; j < al; j++) if(j != i && ((mask >> j)&1))
                    val += 4 * pslef[j][av[i][lo]];
            }
            //cout << val << endl;
            if(hi < av[i].size()){
                for(int j = 0; j < al; j++) if(j != i && ((mask >> j)&1))
                    val += 4 * psrig[j][av[i][hi]];
            }
            dp[mask] = min(dp[mask], dp[mask ^ (1 << i)] + val);
            //cout << "ok " << mask << ' ' << i << ' ' << lo << ' ' << val << ' ' << dp[mask] << endl;
        }
    }

    ll ans = dp[(1 << al) - 1];
    if(ans % 4 == 0)
        cout << ans / 4 << endl;
    else if(ans % 2 == 0)
        cout << ans / 4 << ".5" << endl;
    else
        cout << ans / 4 << ".25" << endl;
}

/*
HEHEHEHIHILOL
ABABABACACDED
*/

Compilation message (stderr)

passes.cpp: In function 'int main()':
passes.cpp:58:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   58 |         for(int j = 1; j < av[i].size(); j++) for(int k = 0; k < al; k++)
      |                        ~~^~~~~~~~~~~~~~
passes.cpp:63:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   63 |         for(int j = 1; j < av[i].size(); j++) for(int k = 0; k < al; k++)
      |                        ~~^~~~~~~~~~~~~~
passes.cpp:91:19: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   91 |             if(hi < av[i].size()){
      |                ~~~^~~~~~~~~~~~~~

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