Submission #625544

#	Time	Username	Problem	Language	Result	Execution time	Memory
625544		Ooops_sorry	Boarding Passes (BOI22_passes)	C++14	100 / 100	1404 ms	354448 KiB

passes

#include<bits/stdc++.h>

using namespace std;

mt19937 rnd(51);

#define ll long long
#define pb push_back
#define ld long double

const int G = 15, N = 1e5 + 10;
const ld INF = 1e18;
ll L[G][G][N], R[G][G][N];
vector<int> pos[G];
int g;

//a * (a - 1) / 4

ld func(int a) {
    return (ld)a * (a - 1) / 4;
}

ll take_val(int mask, int j, int ind, bool f) {
    if (ind < 0 || ind >= pos[j].size()) return 0;
    ll res = 0;
    for (int i = 0; i < g; i++) {
        if (mask & (1 << i)) {
            if (!f) {
                res += L[j][i][pos[j][ind]];
            } else {
                res += R[j][i][pos[j][ind]];
            }
        }
    }
    return res;
}

ld get_ans(int mask, int j, int ind) {
    if (ind >= pos[j].size()) {
        return INF;
    }
    ld val = func(ind + 1) + func((int)(pos[j].size()) - ind - 1) + take_val(mask, j, ind, 0) + take_val(mask, j, ind + 1, 1);
    return val;
}

signed main() {
#ifdef LOCAL
    freopen("input.txt", "r", stdin);
#endif // LOCAL
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    string s;
    cin >> s;
    int n = s.size();
    vector<int> a(n);
    map<char, int> mp;
    for (int i = 0; i < s.size(); i++) {
        if (mp.count(s[i]) == 0) {
            mp[s[i]] = mp.size();
        }
        a[i] = mp[s[i]];
    }
    g = mp.size();
    vector<ld> dp((1 << g), INF);
    for (int i = 0; i < n; i++) {
        pos[a[i]].pb(i);
    }
    for (int i = 0; i < g; i++) {
        for (int l = 0; l < g; l++) {
            ll cnt = 0, res = 0;
            for (int j = 0; j < n; j++) {
                if (i == a[j]) {
                    res += cnt;
                    L[i][l][j] = res;
                } else if (l == a[j]){
                    cnt++;
                }
            }
            cnt = 0, res = 0;
            for (int j = n - 1; j >= 0; j--) {
                if (i == a[j]) {
                    res += cnt;
                    R[i][l][j] = res;
                } else if (l == a[j]){
                    cnt++;
                }
            }
        }
    }
    dp[0] = 0;
    for (int mask = 0; mask < (1 << g); mask++) {
        for (int j = 0; j < g; j++) {
            if (!(mask & (1 << j))) {
                ld bst = func(pos[j].size()) + min(take_val(mask, j, (int)(pos[j].size()) - 1, 0), take_val(mask, j, 0, 1));
                int l = 0, r = (int)(pos[j].size()) - 1;
                while (r - l > 2) {
                    int m1 = l + (r - l) / 3, m2 = r - (r - l) / 3;
                    if (get_ans(mask, j, m1) > get_ans(mask, j, m2)) {
                        l = m1;
                    } else {
                        r = m2;
                    }
                }
                bst = min({bst, get_ans(mask, j, l), get_ans(mask, j, l + 1), get_ans(mask, j, r)});
                dp[mask | (1 << j)] = min(dp[mask | (1 << j)], dp[mask] + bst);
            }
        }
    }
    cout << setprecision(30) << fixed << dp[(1 << g) - 1] << endl;
    return 0;
}

Compilation message (stderr)

passes.cpp: In function 'long long int take_val(int, int, int, bool)':
passes.cpp:24:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   24 |     if (ind < 0 || ind >= pos[j].size()) return 0;
      |                    ~~~~^~~~~~~~~~~~~~~~
passes.cpp: In function 'long double get_ans(int, int, int)':
passes.cpp:39:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   39 |     if (ind >= pos[j].size()) {
      |         ~~~~^~~~~~~~~~~~~~~~
passes.cpp: In function 'int main()':
passes.cpp:57:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   57 |     for (int i = 0; i < s.size(); i++) {
      |                     ~~^~~~~~~~~~

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