Submission #599567

#	Time	Username	Problem	Language	Result	Execution time	Memory
599567		fvogel499	Boarding Passes (BOI22_passes)	C++17	0 / 100	2083 ms	3464 KiB

passes

/*
 * File created on 07/19/2022 at 15:24:35.
 * Link to problem: 
 * Description: 
 * Time complexity: O()
 * Space complexity: O()
 * Status: ---
 * Copyright: Ⓒ 2022 Francois Vogel
*/

#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;

#define pii pair<int, int>
#define f first
#define s second

#define vi vector<int>
#define all(x) x.begin(), x.end()
#define size(x) (int)((x).size())
#define pb push_back
#define ins insert
#define cls clear

#define int ll
#define ll long long
#define ld long double

typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;

signed main() {
    cin.tie(0);
    ios_base::sync_with_stdio(0);
    cout << fixed << setprecision(3);

    string b;
    cin >> b;
    const int n = size(b);
    int gK = 0;
    for (char i : b) if (i-'A'+1 > gK) gK = i-'A'+1;
    vi toPermute;
    for (int i = 0; i < gK; i++) toPermute.pb(i);
    ld offMin = n*n;
    do {
        for (int i = 0; i < n; i++) {
            b[i] = char('A'+toPermute[b[i]-'A']);
        }
        ld res = 0;
        for (int i = 0; i < gK; i++) {
            vi pos;
            for (int j = 0; j < n; j++) if (b[j]-'A' == i) {
                pos.pb(j);
            }
            if (pos.empty()) continue;
            int pref [n];
            for (int j = 0; j < n; j++) pref[j] = (b[j]-'A' < i);
            for (int j = 1; j < n; j++) pref[j] += pref[j-1];
            int suf [n];
            for (int j = 0; j < n; j++) suf[j] = (b[j]-'A' < i);
            for (int j = n-2; j >= 0; j--) suf[j] += suf[j+1];
            for (int j = 0; j < size(pos); j++) {
                int dl = 0;
                if (pos[j]) dl = pref[pos[j]-1];
                int dr = 0;
                if (pos[j]+1 < n) dr = suf[pos[j]+1];
                int cl = j;
                int cr = size(pos)-1-j;
                ld dp [cl+1][cr+1];
                for (int sum = cl+cr; sum >= 0; sum--) {
                    for (int x = 0; x <= cl; x++) {
                        int y = sum-x;
                        if (y < 0 || y > cr) continue;
                        ld tp = cl-x+cr-y+1;
                        dp[x][y] = (ld)(1)/tp*min(dl+x, dr+y);
                        if (x < cl) {
                            dp[x][y] += dp[x+1][y]*(cl-x)/tp;
                        }
                        if (y < cr) {
                            dp[x][y] += dp[x][y+1]*(cr-y)/tp;
                        }
                    }
                }
                res += dp[0][0];
            }
        }
        offMin = min(offMin, res);
        vi invToPermute(gK);
        for (int i = 0; i < gK; i++) invToPermute[toPermute[i]] = i;
        for (int i = 0; i < n; i++) {
            b[i] = char('A'+invToPermute[b[i]-'A']);
        }
    } while (next_permutation(all(toPermute)));
    cout << offMin;

    cout.flush();
    int d = 0;
    d++;
}

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