#include <iostream>
#include <algorithm>
#include <utility>
#include <vector>
#include <stack>
#include <map>
#include <queue>
#include <set>
#include <unordered_set>
#include <unordered_map>
#include <cstring>
#include <cmath>
#include <functional>
#include <cassert>
#include <iomanip>
#include <numeric>
#include <bitset>
#include <sstream>
#include <chrono>
#include <random>
#define ff first
#define ss second
#define PB push_back
#define sz(x) int(x.size())
#define rsz resize
#define fch(xxx, yyy) for (auto xxx : yyy) // abusive notation
#define all(x) (x).begin(),(x).end()
#define eps 1e-9
// more abusive notation (use at your own risk):
//#define int ll
using namespace std;
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;
using vll = vector<ll>;
// debugging
void __print(int x) {std::cerr << x;}
void __print(ll x) {std::cerr << x;} /* remember to uncomment this when not using THE MACRO */
void __print(unsigned x) {std::cerr << x;}
void __print(ull x) {std::cerr << x;}
void __print(float x) {std::cerr << x;}
void __print(double x) {std::cerr << x;}
void __print(ld x) {std::cerr << x;}
void __print(char x) {std::cerr << '\'' << x << '\'';}
void __print(const char *x) {std::cerr << '\"' << x << '\"';}
void __print(const string& x) {std::cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V> void __print(const pair<T, V> &x) {std::cerr << '{'; __print(x.ff); std::cerr << ", "; __print(x.ss); std::cerr << '}';}
template<typename T> void __print(const T& x) {int f = 0; std::cerr << '{'; for (auto &i: x) std::cerr << (f++ ? ", " : ""), __print(i); std::cerr << "}";}
void _print() {std::cerr << "]\n";}
template <typename T, typename... V> void _print(T t, V... v) {__print(t); if (sizeof...(v)) std::cerr << ", "; _print(v...);}
void println() {std::cerr << ">--------------------<" << endl;}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif
// templates
template <class T> bool ckmin(T &a, const T &b) {return b<a ? a = b, 1 : 0;}
template <class T> bool ckmax(T &a, const T &b) {return b>a ? a = b, 1 : 0;}
template <class T> using gr = greater<T>;
template <class T> using vc = vector<T>;
template <class T> using p_q = priority_queue<T>;
template <class T> using pqg = priority_queue<T, vc<T>, gr<T>>;
template <class T1, class T2> using pr = pair<T1, T2>;
mt19937_64 rng_ll(chrono::steady_clock::now().time_since_epoch().count());
int rng(int M) {return (int)(rng_ll()%M);} /*returns any random number in [0, M) */
// const variables
constexpr int INF = (int)2e9;
constexpr int MOD = 998244353;
constexpr ll LL_INF = (ll)3e18;
constexpr int mod = (int)1e9 + 7;
constexpr ll inverse = 500000004LL; // inverse of 2 modulo 1e9 + 7
void setIO(const string& str) {// fast input/output
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
if (str.empty()) return;
freopen((str + ".in").c_str(), "r", stdin);
freopen((str + ".out").c_str(), "w", stdout);
}
vc<pii> findOperations(vector<int> v) {
set<pii> st;
for (int i = 0; i < sz(v); ++i) {
st.insert({v[i], i});
}
vc<pii> ops;
for (int i = 0; i < sz(v); ++i) {
int index = (*st.begin()).ss;
if (index != i) {
ops.PB({index, i}); // swapping the plates
st.erase({v[i], i});
st.insert({v[i], index});
swap(v[i], v[index]);
}
st.erase(st.begin());
}
reverse(all(ops));
return ops;
}
int findSwapPairs(int N, int* s, int M, int* x, int* y, int* p, int* q) {
vc<pii> ans; // answer (the set of operations needed)
int l = 0, r = M; // bounds on binary search
// note that the array can already be sorted, so l is within [0, M]
while (l <= r) {
int mid = (l + r) / 2; // assume that 'mid' moves are taken
vi v(N);
for (int i = 0; i < N; ++i) {
v[i] = s[i]; // stores the apples in their original order on the plates from 0 to N - 1
}
for (int i = 0; i < mid; ++i) {
swap(v[x[i]], v[y[i]]); // now, swap the apples
}
vc<pii> ops = findOperations(v); // operations that make Aizhan win
// ops -> swap the plates under the apples
// if we end up with some permutation [v[0], ... v[N]]
// we want the plates to be in that same orientation
// so we make moves to change [0, 1, 2, ... N] -> [v[0], ... v[N]]
// or, alternatively, we change [v[0], ... v[N]] -> [0, 1, 2, ... N] (1)
// the latter is the correct version because when we swap the plates, we also swap the apples
if (sz(ops) <= mid) {
r = mid - 1;
} else {
l = mid + 1;
}
}
r++;
// redo the above operations
vi v(N);
for (int i = 0; i < N; ++i) {
v[i] = s[i];
}
for (int i = 0; i < r; ++i) {
swap(v[x[i]], v[y[i]]);
}
ans = findOperations(v);
// fill the rest of the operations if needed
while (sz(ans) < r) {
ans.PB({0, 0});
}
vi idx(N); // finding the index of an element a[i] in the array
for (int i = 0; i < N; ++i) {
idx[s[i]] = i;
v[i] = s[i]; // resetting v
}
for (int i = 0; i < r; ++i) {
swap(v[x[i]], v[y[i]]); // performing swap operations
} // v ends up being the swapped apples version
debug(v);
debug(ans);
for (int i = 0; i < r; ++i) { // performing the swap operations for Aizhan
swap(idx[s[x[i]]], idx[s[y[i]]]);
swap(s[x[i]], s[y[i]]);
// v[ans[i].ff] and v[ans[i].ss] are the apples corresponding to the plates that need to be flipped
// idx[v[ans[i].ff]] and idx[v[ans[i].ss]] are the plates corresponding to the apples in the current array
p[i] = idx[v[ans[i].ff]], q[i] = idx[v[ans[i].ss]]; // convert each swap to the index it is currently in and add it to (p, q)
swap(idx[s[p[i]]], idx[s[q[i]]]); // flip/update
swap(s[p[i]], s[q[i]]);
}
return r;
}
void solve() { // testing cases for this algorithm
int N, M;
int s[100005], x[100005], y[100005], p[100005], q[100005];
cin >> N >> M;
for (int i = 0; i < N; ++i) {
cin >> s[i];
}
for (int i = 0; i < M; ++i) {
cin >> x[i] >> y[i];
}
vi v(N);
for (int i = 0; i < N; ++i) {
v[i] = s[i];
}
int moves = findSwapPairs(N, s, M, x, y, p, q);
cout << moves << '\n';
for (int i = 0; i < moves; ++i) {
cout << p[i] << ' ' << q[i] << '\n';
}
for (int i = 0; i < moves; ++i) {
swap(v[x[i]], v[y[i]]);
swap(v[p[i]], v[q[i]]);
}
cout << "resulting array: \n";
for (int i = 0; i < N; ++i) {
cout << v[i] << ' ';
}
cout << '\n';
}
signed main() { // TIME YOURSELF !!!
setIO("");
solve();
}
// TLE -> TRY NOT USING DEFINE INT LONG LONG
// CE -> CHECK LINE 45
// 5000 * 5000 size matrices are kinda big (potential mle)
// Do something, start simpler
Compilation message
sorting.cpp: In function 'void setIO(const string&)':
sorting.cpp:88:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
88 | freopen((str + ".in").c_str(), "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
sorting.cpp:89:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
89 | freopen((str + ".out").c_str(), "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/bin/ld: /tmp/cccNn1so.o: in function `main':
grader.c:(.text.startup+0x0): multiple definition of `main'; /tmp/cckWOLvr.o:sorting.cpp:(.text.startup+0x0): first defined here
collect2: error: ld returned 1 exit status
