Submission #724651

#	Time	Username	Problem	Language	Result	Execution time	Memory
724651		Charizard2021	Boarding Passes (BOI22_passes)	C++17	100 / 100	348 ms	57940 KiB

passes

#include <bits/stdc++.h>
using namespace std;
long long counter1;
long long n;
vector<long long> val;
vector<vector<long long> > l, r;
vector<vector<vector<long long> > > l2, r2;
vector<vector<long long> > groups;
long long dpSolve2(long long already_boarded, long long next, long long split){
    long long ans = 0;
    for (long long t = 0; t < counter1; ++t) {
        long long tmp = l2[next][t][split] + r2[next][t][split];
        if (already_boarded & (1ll << t)) {
            ans += 2 * tmp;
        } else if (t == next) {
            ans += tmp;
        }
    }
    return ans;
}
long long dpSolve(long long already_boarded, long long next){
    long long low = 0, high = groups[next].size() + 1;
    while (high - low > 1) {
        long long mid1 = (high + low) / 2 - 1;
        long long mid2 = mid1 + 1;
        long long c1 = dpSolve2(already_boarded, next, mid1);
        long long c2 = dpSolve2(already_boarded, next, mid2);
        if (c1 < c2){
            high = mid2;
        }
        else{
            low = mid1 + 1;
        }
    }
    long long ans = dpSolve2(already_boarded, next, low);
    return ans;
}
long long calc_costs(){
    vector<long long> dp(1ll << counter1, 1e18);
    dp[0] = 0;
    for (long long i = 1; i < 1ll << counter1; ++i) {
        for (long long t = 0; t < counter1; ++t) {
            if (!(i & (1ll << t))) continue;
            long long parent = i & ~(1ll << t);
            dp[i] = min(dp[i], dp[parent] + dpSolve(parent, t));
        }
    }
    return dp[(1ll << counter1) - 1];
}
int main(){
    string s;
    cin >> s;
    n = s.size();
    map<char, char> types;
    for (char& c: s) {
        if (!types.count(c)) {
            char id = static_cast<char>(types.size());
            types[c] = id;
        }
        c = types[c];
    }
    counter1 = types.size();
    val.assign(counter1, 0);
    for (char c: s){
        val[c]++;
    }
    groups.resize(counter1);
    for (long long i = 0; i < n; ++i) {
        groups[s[i]].push_back(i);
    }

    l = r = vector<vector<long long> >(counter1, vector<long long>(n));
    vector<long long> tmp_cnt(counter1, 0);
    for (size_t i = 0; i < n; ++i) {
        for (size_t j = 0; j < counter1; ++j) {
            l[j][i] = tmp_cnt[j];
            r[j][i] = val[j] - tmp_cnt[j];
        }
        ++tmp_cnt[s[i]];
        --r[s[i]][i];
    }

    vector<vector<long long> > dpLeft, dpRight;
    dpLeft = dpRight = vector<vector<long long> >(counter1, vector<long long>(counter1, 0));
    l2 = r2 = vector<vector<vector<long long> > >(counter1, vector<vector<long long> >(counter1, {0}));
    for (long long i = 0; i < n; i++) {
        for (long long j = 0; j < counter1; ++j) {
            dpLeft[s[i]][j] += l[j][i];
            dpRight[s[n - i - 1]][j] += r[j][n - i - 1];
        }
        for (long long k = 0; k < counter1; ++k) {
            l2[s[i]][k].push_back(dpLeft[s[i]][k]);
            r2[s[n - i - 1]][k].push_back(dpRight[s[n - i - 1]][k]);
        }
    }
    for (long long i = 0; i < counter1; ++i) {
        for (long long j = 0; j < counter1; ++j) {
            reverse(r2[i][j].begin(), r2[i][j].end());
        }
    }
    long long ans = calc_costs();
    cout << ans / 2 << ((ans % 2) ? ".5" : "") << "\n";
}

Compilation message (stderr)

passes.cpp: In function 'int main()':
passes.cpp:74:26: warning: comparison of integer expressions of different signedness: 'size_t' {aka 'long unsigned int'} and 'long long int' [-Wsign-compare]
   74 |     for (size_t i = 0; i < n; ++i) {
      |                        ~~^~~
passes.cpp:75:30: warning: comparison of integer expressions of different signedness: 'size_t' {aka 'long unsigned int'} and 'long long int' [-Wsign-compare]
   75 |         for (size_t j = 0; j < counter1; ++j) {
      |                            ~~^~~~~~~~~~

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