Submission #659943

#	Time	Username	Problem	Language	Result	Execution time	Memory
659943		SansPapyrus683	Zamjene (COCI16_zamjene)	C++17	126 / 140	3924 ms	524288 KiB

zamjene

#include <iostream>
#include <vector>
#include <unordered_map>
#include <algorithm>

using std::cout;
using std::endl;
using std::vector;
using ll = long long;

struct Hash {
    const ll MOD1 = 1e9 + 7;
    const ll MOD2 = 1e9 + 9;

    ll h1, h2;
    Hash(ll h1, ll h2) : h1(h1), h2(h2) { }
    Hash() : h1(0), h2(0) { }

    inline Hash operator+(const Hash& o) {
        return Hash((h1 + o.h1) % MOD1, (h2 + o.h2) % MOD2);
    }

    inline Hash operator-(const Hash& o) {
        return Hash((h1 - o.h1 + MOD1) % MOD1, (h2 - o.h2 + MOD2) % MOD2);
    }

    Hash& operator=(const Hash& h) {
        h1 = h.h1;
        h2 = h.h2;
        return *this;
    }

    inline Hash exp(const ll& n) {
        return Hash(h1 * n % MOD1, h2 * n % MOD2);
    }

    ll hash() const {
        return 1LL * h1 * MOD2 + h2;
    }

    inline vector<Hash> zero_pairs() const {
        return {
            Hash(MOD1 - h1, MOD2 - h2), Hash(-h1, -h2),
            Hash(-h1, MOD2 - h2), Hash(MOD1 - h1, -h2),
        };
    }
};

bool operator<(const Hash& h1, const Hash& h2) {
    return h1.h1 != h2.h1 ? h1.h1 < h2.h1 : h1.h2 < h2.h2;
}

bool operator==(const Hash& h1, const Hash& h2) {
    return h1.h1 == h2.h1 && h1.h2 == h2.h2;
}

bool operator!=(const Hash& h1, const Hash& h2) {
    return h1.h1 != h2.h1 || h1.h2 != h2.h2;
}

namespace std {
 template<> struct hash<Hash> {
  size_t operator()(const Hash& p) const {
   return p.hash();
  }
 };
}

class DominikArray {
    private:
        const ll POW = 1e6 + 3;

        vector<int> arr;
        vector<int> sorted;
        
        vector<int> parent;
        vector<int> size;
        int bad_num = 0;  // # of bad components (used for type 3)

        std::unordered_map<int, Hash> elem_pow;  // raise to the power of the value
        // the current hash of a component
        vector<Hash> hash;
        // the needed hash for a component to be able to be sorted
        vector<Hash> req_hash;
        // the hash differences of the bad components
        std::unordered_map<Hash, ll> bad_diff;
        ll cloud_pairs = 0;  // # of valid component pairs (used for type 4)

        int get_top(int n) {
            return parent[n] == n ? n : (parent[n] = get_top(parent[n]));
        }

        /** checks if a component is unsortable (n is a top node) */
        inline bool is_unsortable(int n) {
            return hash[n] != req_hash[n];
        }

        /** add a bad component to the log & update data accordingly */
        void add_if_bad(int n) {
            if (is_unsortable(n)) {
                // one more bad component
                bad_num++;
                Hash diff = req_hash[n] - hash[n];
                bad_diff[diff] += size[n];
                for (const Hash& zp : diff.zero_pairs()) {
                    cloud_pairs += bad_diff[zp] * size[n];
                }
            }
        }

        void remove_if_bad(int n) {
            if (is_unsortable(n)) {
                bad_num--;
                Hash diff = req_hash[n] - hash[n];
                bad_diff[diff] -= size[n];
                for (const Hash& zp : diff.zero_pairs()) {
                    cloud_pairs -= bad_diff[zp] * size[n];
                }
            }
        }
    public:
        DominikArray(vector<int> arr)
            : arr(arr), parent(arr.size()), size(arr.size(), 1),
              hash(arr.size()), req_hash(arr.size()) {
            sorted = arr;
            std::sort(sorted.begin(), sorted.end());

            // perform coordinate compression
            Hash curr_hsh(1, 1);
            for (int i : sorted) {
                if (!elem_pow.count(i)) {
                    elem_pow[i] = curr_hsh;
                    curr_hsh = curr_hsh.exp(POW);
                }
            }
            
            // set up DSU and the hashes
            for (int i = 0; i < arr.size(); i++) {
                parent[i] = i;
                hash[i] = elem_pow[arr[i]];
                req_hash[i] = elem_pow[sorted[i]];
                add_if_bad(i);
            }
        }

        void swap(int a, int b) {
            int top_a = get_top(a);
            int top_b = get_top(b);

            // temporarily take them out of the bad log (if applicable)
            remove_if_bad(top_a);
            remove_if_bad(top_b);

            // change the hashes of the two components
            hash[top_a] = hash[top_a] + elem_pow[arr[b]] - elem_pow[arr[a]];
            hash[top_b] = hash[top_b] + elem_pow[arr[a]] - elem_pow[arr[b]];

            // add the back (if applicable)
            add_if_bad(top_a);
            add_if_bad(top_b);

            std::swap(arr[a], arr[b]);
        }

        void link(int a, int b) {
            a = get_top(a);
            b = get_top(b);
            if (a == b) {
                return;
            }

            if (size[a] < size[b]) {
                return link(b, a);
            }
            
            remove_if_bad(a);
            remove_if_bad(b);
            
            // standard dsu operations
            size[a] += size[b];
            parent[b] = a;
            
            // add the hash of the smaller component to the bigger one
            hash[a] = hash[a] + hash[b];
            req_hash[a] = req_hash[a] + req_hash[b];

            // since b's merged into a, we just add a back (if applicable)
            add_if_bad(a);
        }

        bool sortable() {
            // for everything to be sortable, there can't be any bad components
            return bad_num == 0;
        }

        ll needed_pair_num() {
            return cloud_pairs;
        }
};

// https://oj.uz/problem/view/COCI16_zamjene (input omitted due to length)
int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(NULL);

    int arr_len;
    int query_num;
    std::cin >> arr_len >> query_num;
    vector<int> arr(arr_len);
    for (int& i : arr) {
        std::cin >> i;
    }
    
    DominikArray array(arr);
    for (int q = 0; q < query_num; q++) {
        int type;
        std::cin >> type;
        int a, b;  // not necessarily used (queries of type 3 & 4)
        switch (type) {
            case 1:
                std::cin >> a >> b;
                array.swap(--a, --b);
                break;
            case 2:
                std::cin >> a >> b;
                array.link(--a, --b);
                break;
            case 3:
                cout << (array.sortable() ? "DA" : "NE") << '\n';
                break;
            case 4:
                cout << array.needed_pair_num() << '\n';
                break;
        };
    }
}

Compilation message (stderr)

zamjene.cpp: In constructor 'DominikArray::DominikArray(std::vector<int>)':
zamjene.cpp:138:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  138 |             for (int i = 0; i < arr.size(); i++) {
      |                             ~~^~~~~~~~~~~~

• Subtask 1: 14 / 14
• Subtask 2: 14 / 14
• Subtask 3: 14 / 14
• Subtask 4: 14 / 14
• Subtask 5: 14 / 14
• Subtask 6: 14 / 14
• Subtask 7: 14 / 14
• Subtask 8: 0 / 14
• Subtask 9: 14 / 14
• Subtask 10: 14 / 14