#include "sorting.h"
#include <bits/stdc++.h>
using namespace std;
#define all(x) (x).begin(), (x).end()
#define FOR(i, a, b) for (int i = a; i < b; i++)
#define each(a, x) for (auto &x : a)
#define srt(x) sort(all(x))
#define sz(x) (int) (x).size()
#define pb push_back
#define trace(x) for (auto &el : x) cout << el << " "
using pi = pair<int, int>;
using vi = vector<int>;
using vpi = vector<pi>;
struct State {
vi cur; int turn;
vpi steps;
};
bool is_sorted(vi inp) {
int n = sz(inp);
vi to_srt = vi(all(inp));
srt(to_srt);
FOR(i, 0, n) {
if (inp[i] != to_srt[i]) return false;
}
return true;
}
/*
N = length of seq
S = initial seq
M = swaps by ermek
X[i], Y[i] = ith swap of ermek
P[i], Q[i] = swaps player makes
function returns R (number of swaps)
*/
int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) {
int n = N;
int R = 1;
vi initial; FOR(i, 0, n) initial.pb(S[i]);
vpi swaps;
int curturn = 0;
FOR(i, 0, n) {
int qidx = 0;
while (initial[qidx] != i) qidx++;
if (qidx == i || qidx <= 1 || i <= 1) continue;
swap(initial[X[curturn]], initial[Y[curturn]]);
curturn++;
swap(initial[qidx], initial[i]);
swaps.pb({i, qidx});
}
R = sz(swaps);
FOR(i, 0, R) {
P[i] = swaps[i].first;
Q[i] = swaps[i].second;
}
queue<State> q;
q.push(State{initial, curturn, {}});
State best;
while (!q.empty()) {
auto cur = q.front();
q.pop();
if (is_sorted(cur.cur)) {
best = cur;
break;
}
vi narr = vi(all(cur.cur));
swap(narr[X[cur.turn]], narr[Y[cur.turn]]);
FOR(i, 0, n) {
if (cur.cur[i] == i) continue;
FOR(j, i + 1, n) {
// if (cur.cur[j] == j) continue;
vi nnarr = vi(all(narr));
swap(nnarr[i], nnarr[j]);
vpi nsteps = vpi(all(cur.steps));
nsteps.pb({i, j});
q.push(State {nnarr, cur.turn + 1, nsteps});
}
}
}
int nR = sz(best.steps);
FOR(i, 0, nR) {
P[i+R] = best.steps[i].first;
Q[i+R] = best.steps[i].second;
}
// trace(best.cur); cout << "\n";
R += nR;
return R;
}
