Submission #775019

#	Time	Username	Problem	Language	Result	Execution time	Memory
775019		daoquanglinh2007	Xor Sort (eJOI20_xorsort)	C++17	25 / 100	99 ms	12408 KiB

xorsort

#include <bits/stdc++.h>
using namespace std;

#define pii pair <int, int>
#define fi first
#define se second
#define mp make_pair

const int NM = 1000;

int N, S, a[NM+5];
vector <pii> ans;

void op(int i, int j){
	ans.push_back(mp(i, j));
	a[i] ^= a[j];
}

int main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin >> N >> S;
	for (int i = 1; i <= N; i++) cin >> a[i];
	while (true){
		bool ok = 1;
		for (int i = 1; i < N; i++)
			if (a[i] > a[i+1]){
				ok = 0;
				op(i+1, i);
				op(i, i+1);
				op(i+1, i);
			}
		if (ok) break;
	}
	cout << ans.size() << '\n';
	for (int i = 0; i < ans.size(); i++)
		cout << ans[i].fi << ' ' << ans[i].se << '\n';
	return 0;
}

Compilation message (stderr)

xorsort.cpp: In function 'int main()':
xorsort.cpp:37:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   37 |  for (int i = 0; i < ans.size(); i++)
      |                  ~~^~~~~~~~~~~~

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