#include <bits/stdc++.h>
#include <unordered_map>
#define ll long long
#define ld long double
#define pll pair <ll,ll>
#define F first
#define S second
#define int ll
#define pb push_back
#define IOS ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0)
using namespace std;
ll n, type;
vector <ll> a;
vector <pll> ans;
void solve1() {
int mn = 2e9;
vector <pll> ans2;
for (int i = 0; i < n - 1; i++)
a[i] ^= a[i + 1];
for (int j = 0; j < n; j++) {
vector <int> aa;
aa = a;
for (int i = 0; i < n; i++)
if (i != j) a[i] ^= a[j];
ans.clear();
vector <int> ab;
ab = aa;
for (int i = 0; i < n - 1; i++)
ans.pb({ i + 1,i + 2 });
for (int i = j + 1; i < n; i++)
{
ans.pb({ i + 1,i });
ab[i] ^= ab[i - 1];
}
for (int i = j - 1; i >= 0; i--)
{
ans.pb({ i + 1,i + 2 });
ab[i] ^= ab[i + 1];
}
a = ab;
unordered_map<int, int> mp;
bool YY = true;
for (int i = 0; i < n; i++)
{
if (mp[a[i]]) { YY = false; break; }
++mp[a[i]];
}
if (YY == false) {
a = aa;
continue;
}
while (1) {
bool found = true;
int mx = -1;
int pos = -1;
for (int i = 0; i < n - 1; i++)
if (a[i] > a[i + 1]) {
pos = i;
break;
}
if (pos < 0) break;
ans.pb({ pos + 2,pos + 1 });
ans.pb({ pos + 1, pos + 2 });
ans.pb({ pos + 2,pos + 1 });
swap(a[pos], a[pos + 1]);
}
if (ans.size() < mn) {
mn = ans.size();
ans2 = ans;
}
a = aa;
}
ans = ans2;
cout << ans.size() << '\n';
for (auto to : ans)
cout << to.F << " " << to.S << '\n';
}
void solve2() {
int m = n;
for (int i = 19; i >= 0; i--)
{
int st = 0;
for (int j = 0; j < m - 1; j++)
{
if (a[j] & (1 << i) && v[j + 1] & (1 << i))
{
st = 1;
ans.push_back({ j, j + 1 });
v[j] ^= v[j + 1];
}
else if (v[j] & (1 << i))
{
st = 1;
ans.push_back({ j + 1, j });
ans.push_back({ j, j + 1 });
v[j + 1] ^= v[j];
v[j] ^= v[j + 1];
}
}
if (st)
m--;
}
cout << ans.size() << '\n';
for (auto to : ans)
cout << to.F << " " << to.S << '\n';
}
int main() {
cin >> n >> type;
a.resize(n);
for (int i = 0; i < n; i++)
cin >> a[i];
if (type == 1) solve1();
else solve2();
}
Compilation message
xorsort.cpp: In function 'void solve1()':
xorsort.cpp:54:9: warning: unused variable 'found' [-Wunused-variable]
54 | bool found = true;
| ^~~~~
xorsort.cpp:55:8: warning: unused variable 'mx' [-Wunused-variable]
55 | int mx = -1;
| ^~
xorsort.cpp:68:18: warning: comparison of integer expressions of different signedness: 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} and 'long long int' [-Wsign-compare]
68 | if (ans.size() < mn) {
| ~~~~~~~~~~~^~~~
xorsort.cpp: In function 'void solve2()':
xorsort.cpp:87:27: error: 'v' was not declared in this scope
87 | if (a[j] & (1 << i) && v[j + 1] & (1 << i))
| ^
At global scope:
cc1plus: error: '::main' must return 'int'
