#1194620 (C++23) No.3775 Distant Swap

• 問題: No.3775 Distant Swap
• ユーザー: igeee
• 提出日時: 2026-10-23 21:55:08
• 言語: C++23 (gcc 15.3.0 + boost 1.92.0 + ACL)
• 結果: AC
• 実行時間: 166 ms / 2,000 ms
• コード長: 6,518 bytes
• コンパイル時間: 6,042 ms
• コンパイル使用メモリ: 427,264 KB
• 実行使用メモリ: 9,824 KB
• 最終ジャッジ日時: 2026-10-23 21:55:42
• 合計ジャッジ時間: 9,563 ms
• ジャッジサーバーID （参考情報）: judge2_0 / judge6_0

ファイルパターン	結果
sample	AC * 3
other	AC * 20

ソースコード

// Templates and Snippets -> https://github.com/igeeeeee/template
#ifdef ONLINE_JUDGE
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#endif
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
using i128 = __int128_t;
using u128 = __uint128_t;
ostream& operator<<(ostream& os, u128 x) {if (x >= 10) os << x / 10;return os << char('0' + x % 10);}
ostream& operator<<(ostream& os, i128 x){if (x < 0){os << '-';return os << (-(u128)x);}return os << (u128)x;}
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
#define rrep(i,start,end) for (ll i = start;i >= (ll)(end);i--)
#define repn(i,end) for(ll i = 0; i <= (ll)(end); i++)
#define reps(i,start,end) for(ll i = start; i < (ll)(end); i++)
#define repsn(i,start,end) for(ll i = start; i <= (ll)(end); i++)
#define each(p,a) for(auto &p:a)
typedef vector<ll> vll;
typedef vector<pair<ll ,ll>> vpll;
typedef vector<vector<pair<ll ,ll>>> vvpll;
typedef vector<vector<ll>> vvll;
typedef vector<vector<vector<ll>>> vvvll;
typedef pair<ll ,ll> pll;
typedef pair<ull,ull> pull;
typedef tuple<ll , ll , ll> tpl3;
typedef tuple<ll , ll , ll , ll> tpl4;
typedef tuple<ll , ll , ll , ll , ll> tpl5;
typedef tuple<ll , ll , ll , ll , ll , ll> tpl6;
#define FI first
#define SE second
#define LL(...) ll __VA_ARGS__; input(__VA_ARGS__)
#define LD(...) ld __VA_ARGS__; input(__VA_ARGS__)
#define Str(...) string __VA_ARGS__; input(__VA_ARGS__)
#define Ch(...) char __VA_ARGS__; input(__VA_ARGS__)
#define all(a)  (a).begin(),(a).end()
#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() );
#define sz(x) (ll)x.size()
// << std::fixed << std::setprecision(10)
const ll INF = 1LL << 60;
const ld EPS = 1e-9;
 
ll lceil(ll a,ll b){if(a%b==0){return a/b;}if(a>=0){return (a/b)+1;}else{return -((-a)/b);}}
ll lfloor(ll a,ll b){if(a%b==0){return a/b;}if(a>=0){return (a/b);}else{return -((-a)/b)-1;}}
inline ll positive_mod(ll a,ll m){return (a % m + m)%m;}
inline ll popcnt(ull a){ return __builtin_popcountll(a);}
//0indexed
inline ll topbit(ll a){assert(a != 0);return 63 - __builtin_clzll(a);}
inline ll smlbit(ll a){assert(a != 0);return __builtin_ctzll(a);}
template<class T> bool chmin(T& a, T b){if(a > b){a = b;return true;}return false;}
template<class T> bool chmax(T& a, T b){if(a < b){a = b;return true;}return false;}
template<typename T> std::istream &operator>>(std::istream&is,std::vector<T>&v){for(T &in:v){is>>in;}return is;}
template<typename T> std::ostream &operator<<(std::ostream&os,const std::vector<T>&v){for(auto it=std::begin(v);it!=std::end(v);){os<<*it<<((++it)!=std::end(v)?" ":"");}return os;}
template<typename T1, typename T2>std::ostream &operator<< (std::ostream &os, std::pair<T1,T2> p){os << "{" << p.first << "," << p.second << "}";return os;}
template<class... T>void input(T&... a){(cin >> ... >> a);}
void print(){cout << endl;}
template<class T, class... Ts>void print(const T& a, const Ts&... b){cout << a;((cout << ' ' << b), ...);cout << endl;}
template<class T> void pspace(const T& a){ cout << a << ' ';}
void perr(){cerr << endl;}
template<class T, class... Ts>void perr(const T& a, const Ts&... b){cerr << a;((cerr << ' ' << b), ...);cerr << endl;}
void yes(bool i = true){ return print(i?"yes":"no"); }
void Yes(bool i = true){ return print(i?"Yes":"No"); }
void YES(bool i = true){ return print(i?"YES":"NO"); }
template <class T> vector<T> &operator++(vector<T> &v) {for(auto &e : v) e++;return v;}
template <class T> vector<T> operator++(vector<T> &v, signed) {auto res = v;for(auto &e : v) e++;return res;}
template <class T> vector<T> &operator--(vector<T> &v) {for(auto &e : v) e--;return v;}
template <class T> vector<T> operator--(vector<T> &v, signed) {auto res = v;for(auto &e : v) e--;return res;}
//grid探索用
vector<ll> _ta = {0,0,1,-1,1,1,-1,-1};
vector<ll> _yo = {1,-1,0,0,1,-1,1,-1};
bool isin(ll now_i,ll now_j,ll h,ll w){return (0<=now_i && now_i < h && 0 <= now_j && now_j < w);}
  
ll lpow(ll x,ll n){ll ans = 1;while(n >0){if(n & 1)ans *= x;x *= x;n >>= 1;}return ans;}
ll Modlpow(ll x,ll n,ll m){ll ans = 1;ll a = x%m;while(n >0){if(n & 1){ans *= a;ans%= m;}a *= a;a %= m;n >>= 1;}return ans;} 
const ll MOD9 = 998244353LL;
const ll MOD10 = 1000000007LL;

void solve();
#ifdef DEBUG
void naive();
string run(void (*f)(), const string& input) {istringstream iss(input);ostringstream oss;auto* cinbuf = cin.rdbuf(iss.rdbuf());auto* coutbuf = cout.rdbuf(oss.rdbuf());cin.clear();f();cout.flush();cin.rdbuf(cinbuf);cout.rdbuf(coutbuf);cin.clear();return oss.str();}

bool check(const string& input) {
  string ans = run(solve, input);istringstream acin(ans);
  string correct = run(naive, input);istringstream ccin(correct);
  // ll x;acin >> x;とかで使える(構築とかの確認用)

  if (ans == correct) return true;//末尾の空白まで完全一致

  cerr << "========== INPUT ==========\n";
  cerr << input;
  cerr << "========== EXPECTED =======\n";
  cerr << correct;
  cerr << "========== ACTUAL =========\n";
  cerr << ans;
  cerr << "===========================\n";
  return false;
}

uint64_t seed = chrono::steady_clock::now().time_since_epoch().count();
mt19937_64 rng(seed);
ll rnd(ll l, ll r){// l 以上 r 以下
  return uniform_int_distribution<ll>(l, r)(rng);
}

void test(){
  rep(tc,100000){
    // ----- テストケース生成(文字列で!!) -----
    string input;
    ll n = rnd(1,10);
    input += to_string(n);
    input += '\n';

    // ----- 比較 -----
    check(input);

    if ((tc+1) % 1000 == 0) {
      cerr << tc+1 << " cases passed\n";
    }
  }
}

void naive(){//cinで受け取りcoutで出力でよい

}
#endif

void solve(){
  LL(n,K);
  vll x(n);cin >> x;
  vll xx(n);
  vpll ans;
  rep(i,K){
    vpll y;
    rep(j,n)if(j % K == i){
      y.push_back({x[j],j});
    }
    vpll z = y;
    sort(all(z));
    rep(j,sz(y)){
      reps(k,j,sz(y)){
        if(y[k] == z[j]){
          for(ll l=k-1;l>=j;l--){
            ans.push_back({i+K*l,i+K*(l+1)});
            swap(y[l],y[l+1]);
          }
          break;
        }
      }
    }
    rep(j,sz(y)){
      auto [val,id] = y[j];
      xx[i+K*j] = val;
    }
  }
  vll xs = x;
  sort(all(xs));
  if(xs != xx){
    cout <<-1<<endl;
    return ;
  }
  cout << sz(ans) << endl;
  for(auto [u,v]:ans){
    u++;
    v++;
    print(u,v);
  }
  

}
 
int main(){
  ios::sync_with_stdio(false);cin.tie(nullptr);
  #ifdef DEBUG
    test();
  #else
    solve();
  #endif
}