#define _CRT_SECURE_NO_WARNINGS #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include //#include "util.h" using namespace std; typedef unsigned uint; typedef long long lint; typedef unsigned long long ulint; //呪文 template ostream& operator << (ostream& ostr, const pair<_KTy, _Ty>& m) { cout << "{" << m.first << ", " << m.second << "}"; return ostr; } template ostream& operator << (ostream& ostr, const map<_KTy, _Ty>& m) { if (m.empty()) { cout << "{ }"; return ostr; } cout << "{" << *m.begin(); for (auto itr = ++m.begin(); itr != m.end(); itr++) { cout << ", " << *itr; } cout << "}"; return ostr; } template ostream& operator << (ostream& ostr, const vector<_Ty>& v) { if (v.empty()) { cout << "{ }"; return ostr; } cout << "{" << v.front(); for (auto itr = ++v.begin(); itr != v.end(); itr++) { cout << ", " << *itr; } cout << "}"; return ostr; } template ostream& operator << (ostream& ostr, const set<_Ty>& s) { if (s.empty()) { cout << "{ }"; return ostr; } cout << "{" << *(s.begin()); for (auto itr = ++s.begin(); itr != s.end(); itr++) { cout << ", " << *itr; } cout << "}"; return ostr; } //template void print(T* v, int N) { if (N == 0) cout << "{ }"; cout << "{" << v[0]; for (int i = 1; i < N; i++) cout << ", " << v[i]; cout << "}"; } #define PI 3.14159265358979323846 #define EPS 1e-8 #define FOR(i,a,b) for(int i=(a);i<(b);++i) #define REP(i,n) FOR(i,0,n) #define all(x) (x).begin(), (x).end() typedef pair pii; stack > cyclic_permutation(vector v, vector w) { stack > res; vector used(v.size(), false); map mp; for (int i = 0; i < v.size(); i++) mp[v[i]] = i; for (int i = 0; i < v.size(); i++) { int j = i; vector cyclic; while (!used[j]) { used[j] = true; cyclic.push_back(j); j = w[mp[j]]; } if (cyclic.size() >= 2) res.push(cyclic); } return res; } stack transposition_product(vector v, vector w) { stack res; stack > cyclic = cyclic_permutation(v, w); while (!cyclic.empty()) { vector t = cyclic.top(); cyclic.pop(); for (int j = 1; j < t.size(); j++) res.push(pii(t[0], t[j])); } return res; } stack fundamental_transposition_product(vector v, vector w) { stack res; stack transposition = transposition_product(v, w); while (!transposition.empty()) { pii p = transposition.top(); transposition.pop(); if (p.first > p.second) swap(p.first, p.second); for (int j = p.first; j < p.second; j++) { if (!res.empty() && res.top().first == j && res.top().second == j + 1) res.pop(); else res.push(pii(j, j + 1)); } for (int j = p.second - 1; j > p.first; j--) { if (!res.empty() && res.top().first == j - 1 && res.top().second == j) res.pop(); else res.push(pii(j - 1, j)); } } return res; } int yuki0326() { int N, K; cin >> N >> K; vector v(N + 1, 0); map mp; for (int i = 1; i <= N; i++) { mp[i] = i; v[i] = i; } for (int i = 0; i < K; i++) { int X, Y; cin >> X >> Y; swap(v[mp[X]], v[mp[Y]]); swap(mp[X], mp[Y]); } vector w(N + 1, 0); for (int i = 1; i <= N; i++) cin >> w[i]; stack step = fundamental_transposition_product(v, w); cout << step.size() << endl; while (!step.empty()) { pii t = step.top(); step.pop(); cout << t.first << " " << t.second << endl; } return 0; } int main() { //clock_t start, end; //start = clock(); yuki0326(); //end = clock(); //printf("%d msec.\n", end - start); return 0; }