제출 #463981

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
463981		tengiz05	Xor Sort (eJOI20_xorsort)	C++17	25 / 100	8 ms	1040 KiB

xorsort

#include <bits/stdc++.h>

std::mt19937 rnd(std::chrono::steady_clock::now().time_since_epoch().count());

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    
    int n, S;
    std::cin >> n >> S;
    
    std::vector<int> a(n);
    for (int i = 0; i < n; i++) {
        std::cin >> a[i];
    }
    
    std::vector<std::pair<int, int>> ans;
    
    auto swap = [&](int i, int j) {
        ans.emplace_back(i, j);
        ans.emplace_back(j, i);
        ans.emplace_back(i, j);
        a[i] ^= a[j];
        a[j] ^= a[i];
        a[i] ^= a[j];
    };
    
    for (int i = 0; i < 1000; i++) {
        int l = rnd() % (n - 1);
        int r = l + 1;
        ans.emplace_back(l, r);
        a[l] ^= a[r];
    }
    
    std::vector<int> bad;
    auto unique = [&]() {
        // return std::set<int>(a.begin(), a.end()).size() == n;
        std::map<int, std::vector<int>> m;
        for (int i = 0; i < n; i++) {
            m[a[i]].push_back(i);
        }
        bad.clear();
        for (auto [x, y] : m) {
            if (y.size() > 1) {
                for (auto t : y) bad.push_back(t);
            }
        }
        return bad.empty();
    };
    
    while (!unique()) {
        int l = rnd() % (n - 1);
        int r = l + 1;
        ans.emplace_back(l, r);
        a[l] ^= a[r];
    }
    
    std::vector<int> b = a;
    std::sort(b.begin(), b.end());
    if (S == 1) {
        for (int i = 0; i < n; i++) {
            for (int j = n - 1; j >= 0; j--) {
                if (a[j] != b[j]) {
                    int pos = std::find(a.begin(), a.end(), b[j]) - a.begin();
                    for (; pos < j; pos++) {
                        swap(pos, pos + 1);
                    }
                }
            }
        }
    }
    
    std::cout << ans.size() << "\n";
    for (auto [i, j] : ans) {
        std::cout << i + 1 << " " << j + 1 << "\n";
    }
    
    return 0;
}

• Subtask 1: 25 / 25
• Subtask 2: 0 / 35
• Subtask 3: 0 / 40