#include "sorting.h"
#include<bits/stdc++.h>
using namespace std;
int solve(vector<int> v){
vector<bool> seen(v.size(), false);
int res = 0;
for (int i=0; i<v.size(); i++){
if (seen[i]) continue;
seen[i] = true;
int j = i;
while (!seen[v[j]]){
res++;
j = v[j];
seen[j] = true;
}
}
return res;
}
int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]){
vector<int> f(N), g(N);
for (int i=0; i<N; i++){
f[i] = i;
g[i] = i;
}
int l = -1, r = M;
while (l != r-1){
int m = (l+r)/2;
vector<int> gx = g;
for (int i=0; i<m; i++) swap(gx[X[i]], gx[Y[i]]);
vector<int> v(N);
for (int i=0; i<N; i++) v[i] = S[gx[i]];
if (solve(v) <= m) r = m;
else l = m;
}
for (int i=0; i<r; i++){
swap(g[X[i]], g[Y[i]]);
swap(f[g[Y[i]]], f[g[X[i]]]);
}
vector<int> v(N);
for (int i=0; i<N; i++) v[i] = S[g[i]];
unordered_set<int> us;
for (int i=0; i<N; i++) us.insert(i);
for (int i=0; i<r; i++){
swap(f[X[i]], f[Y[i]]);
swap(g[f[Y[i]]], g[f[X[i]]]);
P[i] = 0;
Q[i] = 0;
vector<int> del;
for (int j : us){
if (v[j] == j) del.push_back(j);
if (v[j] != j){
P[i] = g[j];
Q[i] = g[v[j]];
swap(v[j], v[v[j]]);
break;
}
}
for (int j : del) us.erase(j);
}
return r;
}
