Submission #1057290

#	Time	Username	Problem	Language	Result	Execution time	Memory
1057290		juicy	Xor Sort (eJOI20_xorsort)	C++17	100 / 100	6 ms	1104 KiB

xorsort

#include <bits/stdc++.h>

using namespace std;

#ifdef LOCAL
#include "debug.h"
#else
#define debug(...) 42
#endif

int main() {
  ios::sync_with_stdio(false); cin.tie(nullptr);

  int n, S;
  cin >> n >> S;
  vector<int> a(n);
  for (int i = 0; i < n; ++i) {
    cin >> a[i];
  }
  vector<array<int, 2>> res;
  auto add = [&](int u, int v) {
    res.push_back({u + 1, v + 1});
  }; 
  if (S == 1) {
    for (int i = n - 1; i >= 0; --i) {
      int p = -1;
      for (int j = 0; j <= i; ++j) {
        if (p == -1 || a[p] < a[j]) {
          p = j;
        }
        if (j) {
          add(j - 1, j);
        } 
      }
      for (int j = p + 1; j <= i; ++j) {
        add(j, j - 1);
      }
      for (int j = p - 2; j >= 0; --j) {
        add(j, j + 1);
      }
      for (int j = p; j + 1 < n; ++j) {
        swap(a[j], a[j + 1]);
      }
    }
    for (int i = n - 2; i >= 0; --i) {
      add(i, i + 1);
    }
  } else {
    int m = n;
    for (int j = 19; j >= 0; --j) {
      for (int i = 0; i < m; ++i) {
        if (a[i] >> j & 1) {
          while (i + 1 < m) {
            if (!(a[i + 1] >> j & 1)) {
              a[i + 1] ^= a[i];
              add(i + 1, i);
            }
            a[i] ^= a[i + 1];
            add(i, i + 1);
            ++i;
          }
          --m;
        }
      }
    }
  }
  cout << res.size() << "\n";
  for (auto [x, y] : res) {
    cout << x << " " << y << "\n";
  }
  return 0;
}

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