Submission #420275

#	Time	Username	Problem	Language	Result	Execution time	Memory
420275		acm	Xor Sort (eJOI20_xorsort)	C++14	0 / 100	1 ms	204 KiB

xorsort

#include <bits/stdc++.h>
#define speed                   \
  ios_base::sync_with_stdio(0); \
  cin.tie(0);                   \
  cout.tie(0);
#define precision     \
  cout.precision(30); \
  cerr.precision(10);
#define ll long long
#define ld long double
#define pll pair<ll, ll>
#define pii pair<int, int>
#define forn(n) for (int i = 1; i <= n; i++)
#define forlr(l, r) for (int i = l; i != r; (l > r ? i-- : i++))
#define pb(x) push_back(x)
#define sz(x) (int)x.size()
#define mp(x, y) make_pair(x, y)
#define all(x) x.begin(), x.end()
#define pc(x) __builtin_popcount(x)
#define pcll(x) __builtin_popcountll(x)
#define F first
#define S second
using namespace std;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
void ioi(string name) {
  freopen((name + ".in").c_str(), "r", stdin);
  freopen((name + ".out").c_str(), "w", stdout);
}
int n, s, a[1005];
vector<pair<int, int>> v;
int main() {
  speed;
  precision;
  // code
  cin >> n >> s;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  while (true) {
    int ok = 1;
    for (int i = 1; i < n; i++) {
      if (a[i] < a[i + 1]) {
        v.pb(mp(i + 1, i));
        v.pb(mp(i, i + 1));
        v.pb(mp(i + 1, i));
        a[i + 1] ^= a[i];
        a[i] ^= a[i + 1];
        a[i + 1] ^= a[i];
        ok = 0;
        break;
      }
    }
    if (ok) break;
  }
  cout << sz(v) << "\n";
  for (auto x : v) cout << x.S << " " << x.F << "\n";
    // endl
#ifndef ONLINE_JUDGE
  cerr << "\nTime elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
#endif
  return 0;
}

Compilation message (stderr)

xorsort.cpp: In function 'void ioi(std::string)':
xorsort.cpp:26:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   26 |   freopen((name + ".in").c_str(), "r", stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
xorsort.cpp:27:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |   freopen((name + ".out").c_str(), "w", stdout);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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