Submission #1206527

#	Time	Username	Problem	Language	Result	Execution time	Memory
1206527		Triseedot	Group Photo (JOI21_ho_t3)	C++20	100 / 100	514 ms	196528 KiB

Main

// Made by ordinary newbie

#pragma region setup
#include <bits/stdc++.h>
#include <random>
#include <chrono>
using namespace std;

// variables
#define int long long
using ld = long double;
using ll = long long;
using ull = unsigned long long;
template<typename T>
using min_heap = priority_queue<T, vector<T>, greater<T>>;
// bitwise operations
#define cnt_bit(n) __builtin_popcountll(n)
#define low_bit(n) ((n) & (-(n)))
#define bit(n, i) (((n) >> (i)) & 1)
#define set_bit(n, i) ((n) | (1ll << (i)))
#define reset_bit(n, i) ((n) & ~(1ll << (i)))
#define flip_bit(n, i) ((n) ^ (1ll << (i)))
// math
#define sqr(n) ((n) * (n))
int log2_floor(ull n) {
    return n ? __builtin_clzll(1) - __builtin_clzll(n) : -1;
}
const ll INF = 1e18;
// utils
#define len(x) (int) x.size()
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
template <typename T>
istream& operator>>(istream& is, vector<T>& v) {
    for(auto& el : v) {
        is >> el;
    }
    return is;
}
template <typename T>
ostream& operator<<(ostream& os, const vector<T>& v) {
    for (int i = 0; i < len(v); i++) {
        if (i) os << ' ';
        os << v[i];
    }
    return os;
}
template<class... Args>
auto create(size_t n, Args&&... args) {
    if constexpr(sizeof...(args) == 1) {
        return vector(n, args...);
    }
    else {
        return vector(n, create(args...));
    }
}
struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
    size_t operator()(pair<int, int> x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x.first + FIXED_RANDOM) ^ splitmix64(x.second + FIXED_RANDOM);
    }
};
template<typename T, typename U>
bool chmin(T& a, const U b) {
    if (b < a) {
        a = b;
        return true;
    }
    return false;
}
template<typename T, typename U>
bool chmax(T& a, const U b) {
    if (b > a) {
        a = b;
        return true;
    }
    return false;
}
template<typename T>
void compress(vector<T>& v) {
    int n = len(v);
    vector<pair<T, int>> u(n);
    for (int i = 0; i < n; i++) {
        u[i] = {v[i], i};
    }
    sort(all(u));
    int curr = 0;
    for (int i = 0; i < n; i++) {
        if (i != 0 && u[i].first != u[i - 1].first) curr++;
        v[u[i].second] = curr;
    }
}
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
#pragma endregion

struct FenwickTree {
    int n;
    vector<int> tree;

    FenwickTree() {}
    FenwickTree(int N) {
        n = N;
        tree.assign(n + 1, 0);
    }

    void increase(int i, int val) {
        for (i = i + 1; i <= n; i += low_bit(i)) {
            tree[i] += val;
        }
    }
    FenwickTree(vector<int> a) {
        n = len(a);
        tree.assign(n + 1, 0);
        for (int i = 0; i < n; i++) {
            increase(i, a[i]);
        }
    }

    int get(int i) {
        int ans = 0;
        for (i = i; i > 0; i -= low_bit(i)) {
            ans += tree[i];
        }
        return ans;
    }
    int get(int l, int r) {
        return get(r) - get(l);
    }
};

void solve() {
    int n;
    cin >> n;
    vector<int> p(n);
    cin >> p;
    for (int i = 0; i < n; i++) {
        p[i]--;
    }
    vector<int> pi(n);
    for (int i = 0; i < n; i++) {
        pi[p[i]] = i;
    }

    vector trans = create(n, n + 1, 0ll);
    FenwickTree tree1, tree2;
    for (int l = 0; l < n; l++) {
        tree1 = tree2 = FenwickTree(n);
        for (int i = l; i < n; i++) {
            tree1.increase(pi[i], 1);
        }
        int curr = 0;
        for (int r = l + 1; r <= n; r++) {
            curr -= tree2.get(pi[r - 1] + 1, n);
            curr += tree1.get(pi[r - 1]);
            tree2.increase(pi[r - 1], 1);
            trans[l][r] = curr;
        }
    }

    vector<int> dp(n + 1, INF);
    dp[0] = 0;
    for (int i = 0; i < n; i++) {
        for (int j = i + 1; j <= n; j++) {
            chmin(dp[j], dp[i] + trans[i][j]);
        }
    }

    cout << dp[n] << '\n';
}

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

    int tt = 1;
    //cin >> tt;
    for (int i = 1; i <= tt; i++) {
        solve();
    }
}

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 32 / 32
• Subtask 4: 20 / 20
• Subtask 5: 36 / 36