#ifdef DEBUG #define _GLIBCXX_DEBUG #define CERR( ANSWER ) cerr << ANSWER << endl; #define LIBRARY_SEARCH if( LibrarySearch() != 0 ){ QUIT; }; #else #pragma GCC optimize ( "O3" ) #pragma GCC optimize( "unroll-loops" ) #pragma GCC target ( "sse4.2,fma,avx2,popcnt,lzcnt,bmi2" ) #define CERR( ANSWER ) #define LIBRARY_SEARCH #endif #include using namespace std; using uint = unsigned int; using ll = long long; using ull = unsigned long long; #define ATT __attribute__( ( target( "sse4.2,fma,avx2,popcnt,lzcnt,bmi2" ) ) ) #define TYPE_OF( VAR ) decay_t #define UNTIE ios_base::sync_with_stdio( false ); cin.tie( nullptr ) #define CEXPR( LL , BOUND , VALUE ) constexpr LL BOUND = VALUE #define CIN( LL , A ) LL A; cin >> A #define ASSERT( A , MIN , MAX ) assert( ( MIN ) <= A && A <= ( MAX ) ) #define CIN_ASSERT( A , MIN , MAX ) CIN( TYPE_OF( MAX ) , A ); ASSERT( A , MIN , MAX ) #define GETLINE( A ) string A; getline( cin , A ) #define GETLINE_SEPARATE( A , SEPARATOR ) string A; getline( cin , A , SEPARATOR ) #define FOR( VAR , INITIAL , FINAL_PLUS_ONE ) for( TYPE_OF( FINAL_PLUS_ONE ) VAR = INITIAL ; VAR < FINAL_PLUS_ONE ; VAR ++ ) #define FOREQ( VAR , INITIAL , FINAL ) for( TYPE_OF( FINAL ) VAR = INITIAL ; VAR <= FINAL ; VAR ++ ) #define FOREQINV( VAR , INITIAL , FINAL ) for( TYPE_OF( INITIAL ) VAR = INITIAL ; VAR >= FINAL ; VAR -- ) #define FOR_ITR( ARRAY , ITR , END ) for( auto ITR = ARRAY .begin() , END = ARRAY .end() ; ITR != END ; ITR ++ ) #define REPEAT( HOW_MANY_TIMES ) FOR( VARIABLE_FOR_REPEAT , 0 , HOW_MANY_TIMES ) #define QUIT return 0 #define COUT( ANSWER ) cout << ( ANSWER ) << "\n" #define RETURN( ANSWER ) COUT( ANSWER ); QUIT #define SET_PRECISION( PRECISION ) cout << fixed << setprecision( PRECISION ) #define DOUBLE( PRECISION , ANSWER ) SET_PRECISION << ( ANSWER ) << "\n"; QUIT template inline T Absolute( const T& a ){ return a > 0 ? a : -a; } template inline T Residue( const T& a , const T& p ){ return a >= 0 ? a % p : ( a % p ) + p; } #define POWER( ANSWER , ARGUMENT , EXPONENT ) \ static_assert( ! is_same::value && ! is_same::value ); \ TYPE_OF( ARGUMENT ) ANSWER{ 1 }; \ { \ TYPE_OF( ARGUMENT ) ARGUMENT_FOR_SQUARE_FOR_POWER = ( ARGUMENT ); \ TYPE_OF( EXPONENT ) EXPONENT_FOR_SQUARE_FOR_POWER = ( EXPONENT ); \ while( EXPONENT_FOR_SQUARE_FOR_POWER != 0 ){ \ if( EXPONENT_FOR_SQUARE_FOR_POWER % 2 == 1 ){ \ ANSWER *= ARGUMENT_FOR_SQUARE_FOR_POWER; \ } \ ARGUMENT_FOR_SQUARE_FOR_POWER *= ARGUMENT_FOR_SQUARE_FOR_POWER; \ EXPONENT_FOR_SQUARE_FOR_POWER /= 2; \ } \ } \ #define POWER_MOD( ANSWER , ARGUMENT , EXPONENT , MODULO ) \ ll ANSWER{ 1 }; \ { \ ll ARGUMENT_FOR_SQUARE_FOR_POWER = ( MODULO + ( ( ARGUMENT ) % MODULO ) ) % MODULO; \ TYPE_OF( EXPONENT ) EXPONENT_FOR_SQUARE_FOR_POWER = ( EXPONENT ); \ while( EXPONENT_FOR_SQUARE_FOR_POWER != 0 ){ \ if( EXPONENT_FOR_SQUARE_FOR_POWER % 2 == 1 ){ \ ANSWER = ( ANSWER * ARGUMENT_FOR_SQUARE_FOR_POWER ) % MODULO; \ } \ ARGUMENT_FOR_SQUARE_FOR_POWER = ( ARGUMENT_FOR_SQUARE_FOR_POWER * ARGUMENT_FOR_SQUARE_FOR_POWER ) % MODULO; \ EXPONENT_FOR_SQUARE_FOR_POWER /= 2; \ } \ } \ #define FACTORIAL_MOD( ANSWER , ANSWER_INV , INVERSE , MAX_INDEX , CONSTEXPR_LENGTH , MODULO ) \ static ll ANSWER[CONSTEXPR_LENGTH]; \ static ll ANSWER_INV[CONSTEXPR_LENGTH]; \ static ll INVERSE[CONSTEXPR_LENGTH]; \ { \ ll VARIABLE_FOR_PRODUCT_FOR_FACTORIAL = 1; \ ANSWER[0] = VARIABLE_FOR_PRODUCT_FOR_FACTORIAL; \ FOREQ( i , 1 , MAX_INDEX ){ \ ANSWER[i] = ( VARIABLE_FOR_PRODUCT_FOR_FACTORIAL *= i ) %= MODULO; \ } \ ANSWER_INV[0] = ANSWER_INV[1] = INVERSE[1] = VARIABLE_FOR_PRODUCT_FOR_FACTORIAL = 1; \ FOREQ( i , 2 , MAX_INDEX ){ \ ANSWER_INV[i] = ( VARIABLE_FOR_PRODUCT_FOR_FACTORIAL *= INVERSE[i] = MODULO - ( ( ( MODULO / i ) * INVERSE[MODULO % i] ) % MODULO ) ) %= MODULO; \ } \ } \ // 通常の二分探索その1 // EXPRESSIONがANSWERの狭義単調増加関数の時、EXPRESSION >= TARGETを満たす最小の整数を返す。 // 広義単調増加関数を扱いたい時は等号成立の処理を消して続く>に等号を付ける。 #define BS1( ANSWER , MINIMUM , MAXIMUM , EXPRESSION , TARGET ) \ static_assert( ! is_same::value && ! is_same::value ); \ ll ANSWER; \ { \ ll VARIABLE_FOR_BINARY_SEARCH_L = MINIMUM; \ ll VARIABLE_FOR_BINARY_SEARCH_U = MAXIMUM; \ ANSWER = ( VARIABLE_FOR_BINARY_SEARCH_L + VARIABLE_FOR_BINARY_SEARCH_U ) / 2; \ ll VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH; \ while( VARIABLE_FOR_BINARY_SEARCH_L != VARIABLE_FOR_BINARY_SEARCH_U ){ \ VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH = ( EXPRESSION ) - ( TARGET ); \ CERR( VARIABLE_FOR_BINARY_SEARCH_L << "<=" << ANSWER << "<=" << VARIABLE_FOR_BINARY_SEARCH_U << ":" << EXPRESSION << "-" << TARGET << "=" << VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH ); \ if( VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH == 0 ){ \ break; \ } else { \ if( VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH > 0 ){ \ VARIABLE_FOR_BINARY_SEARCH_U = ANSWER; \ } else { \ VARIABLE_FOR_BINARY_SEARCH_L = ANSWER + 1; \ } \ ANSWER = ( VARIABLE_FOR_BINARY_SEARCH_L + VARIABLE_FOR_BINARY_SEARCH_U ) / 2; \ } \ } \ CERR( VARIABLE_FOR_BINARY_SEARCH_L << "<=" << ANSWER << "<=" << VARIABLE_FOR_BINARY_SEARCH_U << ":" << EXPRESSION << "-" << TARGET << ">=0" ); \ } \ // 通常の二分探索その2 // EXPRESSIONがANSWERの狭義単調増加関数の時、EXPRESSION <= TARGETを満たす最大の整数を返す。 // 広義単調増加関数を扱いたい時は等号成立の処理を消して続く<に等号を付ける。 #define BS2( ANSWER , MINIMUM , MAXIMUM , EXPRESSION , TARGET ) \ static_assert( ! is_same::value && ! is_same::value ); \ ll ANSWER; \ { \ ll VARIABLE_FOR_BINARY_SEARCH_L = MINIMUM; \ ll VARIABLE_FOR_BINARY_SEARCH_U = MAXIMUM; \ ANSWER = ( VARIABLE_FOR_BINARY_SEARCH_L + VARIABLE_FOR_BINARY_SEARCH_U ) / 2; \ ll VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH; \ while( VARIABLE_FOR_BINARY_SEARCH_L != VARIABLE_FOR_BINARY_SEARCH_U ){ \ VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH = ( EXPRESSION ) - ( TARGET ); \ CERR( VARIABLE_FOR_BINARY_SEARCH_L << "<=" << ANSWER << "<=" << VARIABLE_FOR_BINARY_SEARCH_U << ":" << EXPRESSION << "-" << TARGET << "=" << VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH ); \ if( VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH == 0 ){ \ break; \ } else { \ if( VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH < 0 ){ \ VARIABLE_FOR_BINARY_SEARCH_L = ANSWER; \ } else { \ VARIABLE_FOR_BINARY_SEARCH_U = ANSWER - 1; \ } \ ANSWER = ( VARIABLE_FOR_BINARY_SEARCH_L + 1 + VARIABLE_FOR_BINARY_SEARCH_U ) / 2; \ } \ } \ CERR( VARIABLE_FOR_BINARY_SEARCH_L << "<=" << ANSWER << "<=" << VARIABLE_FOR_BINARY_SEARCH_U << ":" << EXPRESSION << "-" << TARGET << "<=0" ); \ } \ // 通常の二分探索その3 // EXPRESSIONがANSWERの狭義単調減少関数の時、EXPRESSION >= TARGETを満たす最大の整数を返す。 // 広義単調増加関数を扱いたい時は等号成立の処理を消して続く>に等号を付ける。 #define BS3( ANSWER , MINIMUM , MAXIMUM , EXPRESSION , TARGET ) \ static_assert( ! is_same::value && ! is_same::value ); \ ll ANSWER; \ { \ ll VARIABLE_FOR_BINARY_SEARCH_L = MINIMUM; \ ll VARIABLE_FOR_BINARY_SEARCH_U = MAXIMUM; \ ANSWER = ( VARIABLE_FOR_BINARY_SEARCH_L + VARIABLE_FOR_BINARY_SEARCH_U ) / 2; \ ll VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH; \ while( VARIABLE_FOR_BINARY_SEARCH_L != VARIABLE_FOR_BINARY_SEARCH_U ){ \ VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH = ( EXPRESSION ) - ( TARGET ); \ CERR( VARIABLE_FOR_BINARY_SEARCH_L << "<=" << ANSWER << "<=" << VARIABLE_FOR_BINARY_SEARCH_U << ":" << EXPRESSION << "-" << TARGET << "=" << VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH ); \ if( VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH == 0 ){ \ break; \ } else { \ if( VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH > 0 ){ \ VARIABLE_FOR_BINARY_SEARCH_L = ANSWER; \ } else { \ VARIABLE_FOR_BINARY_SEARCH_U = ANSWER - 1; \ } \ ANSWER = ( VARIABLE_FOR_BINARY_SEARCH_L + 1 + VARIABLE_FOR_BINARY_SEARCH_U ) / 2; \ } \ } \ CERR( VARIABLE_FOR_BINARY_SEARCH_L << "<=" << ANSWER << "<=" << VARIABLE_FOR_BINARY_SEARCH_U << ":" << EXPRESSION << "-" << TARGET << ">=0" ); \ } \ // 通常の二分探索その4 // EXPRESSIONがANSWERの狭義単調減少関数の時、EXPRESSION <= TARGETを満たす最小の整数を返す。 // 広義単調増加関数を扱いたい時は等号成立の処理を消して続く<に等号を付ける。 #define BS4( ANSWER , MINIMUM , MAXIMUM , EXPRESSION , TARGET ) \ static_assert( ! is_same::value && ! is_same::value ); \ ll ANSWER; \ { \ ll VARIABLE_FOR_BINARY_SEARCH_L = MINIMUM; \ ll VARIABLE_FOR_BINARY_SEARCH_U = MAXIMUM; \ ANSWER = ( VARIABLE_FOR_BINARY_SEARCH_L + VARIABLE_FOR_BINARY_SEARCH_U ) / 2; \ ll VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH; \ while( VARIABLE_FOR_BINARY_SEARCH_L != VARIABLE_FOR_BINARY_SEARCH_U ){ \ VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH = ( EXPRESSION ) - ( TARGET ); \ CERR( VARIABLE_FOR_BINARY_SEARCH_L << "<=" << ANSWER << "<=" << VARIABLE_FOR_BINARY_SEARCH_U << ":" << EXPRESSION << "-" << TARGET << "=" << VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH ); \ if( VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH == 0 ){ \ break; \ } else { \ if( VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH < 0 ){ \ VARIABLE_FOR_BINARY_SEARCH_U = ANSWER; \ } else { \ VARIABLE_FOR_BINARY_SEARCH_L = ANSWER + 1; \ } \ ANSWER = ( VARIABLE_FOR_BINARY_SEARCH_L + VARIABLE_FOR_BINARY_SEARCH_U ) / 2; \ } \ } \ CERR( VARIABLE_FOR_BINARY_SEARCH_L << "<=" << ANSWER << "<=" << VARIABLE_FOR_BINARY_SEARCH_U << ":" << EXPRESSION << "-" << TARGET << "<=0" ); \ } \ // 二進法の二分探索 // EXPRESSIONがANSWERの狭義単調増加関数の時、EXPRESSION <= TARGETを満たす最大の整数を返す。 #define BBS( ANSWER , MINIMUM , MAXIMUM , EXPRESSION , TARGET ) \ ll ANSWER = MINIMUM; \ { \ ll VARIABLE_FOR_POWER_FOR_BINARY_SEARCH = 1; \ ll VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH = ( MAXIMUM ) - ANSWER; \ while( VARIABLE_FOR_POWER_FOR_BINARY_SEARCH <= VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH ){ \ VARIABLE_FOR_POWER_FOR_BINARY_SEARCH *= 2; \ } \ VARIABLE_FOR_POWER_FOR_BINARY_SEARCH /= 2; \ ll VARIABLE_FOR_ANSWER_FOR_BINARY_SEARCH = ANSWER; \ while( VARIABLE_FOR_POWER_FOR_BINARY_SEARCH != 0 ){ \ ANSWER = VARIABLE_FOR_ANSWER_FOR_BINARY_SEARCH + VARIABLE_FOR_POWER_FOR_BINARY_SEARCH; \ VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH = ( EXPRESSION ) - ( TARGET ); \ if( VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH == 0 ){ \ VARIABLE_FOR_ANSWER_FOR_BINARY_SEARCH = ANSWER; \ break; \ } else if( VARIABLE_FOR_DIFFERENCE_FOR_BINARY_SEARCH < 0 ){ \ VARIABLE_FOR_ANSWER_FOR_BINARY_SEARCH = ANSWER; \ } \ VARIABLE_FOR_POWER_FOR_BINARY_SEARCH /= 2; \ } \ ANSWER = VARIABLE_FOR_ANSWER_FOR_BINARY_SEARCH; \ } \ // 圧縮用 #define TE template #define TY typename #define US using #define ST static #define IN inline #define CL class #define PU public #define OP operator #define CE constexpr #define CO const #define NE noexcept #define RE return #define WH while #define VO void #define VE vector #define LI list #define BE begin #define EN end #define SZ size #define MO move #define TH this #define CRI CO int& #define CRUI CO uint& #define CRL CO ll& int LibrarySearch() { CERR( "ライブラリーを探索しますか?[y/n]" ); CIN( string , reply ); if( reply == "n" ){ CERR( "ライブラリーを探索せずに続行します。" ); CERR( "" ); return 0; } else if( reply != "y" ){ CERR( "y/nのいずれかで答えてください。" ); CERR( "終了します。" ); CERR( "" ); return -1; } CERR( "" ); CERR( "ライブラリーを探索します。" ); CERR( "問題の種類を番号で指定してください;" ); vector problems = { "数に関する問題。" , "配列に関する問題。" , "文字列に関する問題。" , "順列に関する問題。" , "グラフに関する問題。" , "格子点に関する問題。" }; int problems_size = problems.size(); FOR( i , 0 , problems_size ){ CERR( i << ": " << problems[i] ); } CIN( int , num ); CERR( "" ); if( num < 0 || num >= problems_size ){ cerr << "返答は" << problems_size - 1 << "以下の非負整数にしてください。"; CERR( "終了します。" ); CERR( "" ); return -1; } else if( num == 0 ){ CERR( "入力は1つの数か、1つの数と法を表す数ですか?[y/n/c]" ); cin >> reply; CERR( "" ); if( reply == "y" ){ CERR( "まずは小さい入力の場合を愚直に計算し、OEISで検索しましょう。" ); CERR( "https://oeis.org/?language=japanese" ); CERR( "" ); CERR( "次に出力の定義と等価な式を考察しましょう。" ); CERR( "もし単調ならば、冪乗や階乗を検討しましょう。" ); CERR( "もし定義にp進法が使われていれば、探索アルゴリズムを検討しましょう。" ); CERR( "もし入力が素数に近い場合に規則性があれば、p進付値、p進法、オイラー関数、約数の個数などを検討しましょう。" ); } else if( reply == "n" ){ CERR( "このケースのライブラリー探索は未実装です。" ); } else if( reply == "c" ){ CERR( "終了します。" ); CERR( "" ); return -1; } else { CERR( "y/n/cのいずれかで答えてください。" ); CERR( "終了します。" ); CERR( "" ); return -1; } CERR( "" ); CERR( "マルチテストケースの場合は以下の前計算を検討しましょう;" ); CERR( "素数列挙、約数列挙、サブゴールとなる関係式を満たす解列挙。" ); } else if( num == 3 ){ CERR( "符号の計算は転倒数の計算に帰着させましょう。" ); CERR( "符号と何かの積の和は行列式に帰着させましょう。余因子展開のメモ化再帰でO(N 2^N)です。" ); CERR( "" ); CERR( "1つの順列の転倒数は、" ); CERR( "- O(N^2)が通るなら愚直な二重ループ" ); CERR( "- O(N log_2 N)が必要なら可換群に対するBIT" ); CERR( " \\Mathematics\\SetTheory\\DirectProduct\\AffineSpace\\BIT" ); CERR( "で計算しましょう。" ); CERR( "" ); CERR( "条件を満たす順列全体をわたる転倒数の総和は、各i class BIT { private: T m_fenwick[N + 1]; public: inline BIT(); BIT( const T ( & a )[N] ); inline void Set( const int& i , const T& n ); inline BIT& operator+=( const T ( & a )[N] ); void Add( const int& i , const T& n ); T InitialSegmentSum( const int& i_final ) const; inline T IntervalSum( const int& i_start , const int& i_final ) const; // operator+=の単位元T()より小さくない要素のみを成分に持つ場合のみサポート。 // InitialSegmentSum( i )がn以上となるiが存在する場合にその最小値を2進法で探索。 int BinarySearch( const T& n ) const; // IntervalSum( i_start , i )がt以上となるi_start以上のiが存在する場合にその最小値を2進法で探索。 inline int BinarySearch( const int& i_start , const T& n ) const; }; template inline BIT::BIT() : m_fenwick() {} template BIT::BIT( const T ( & a )[N] ) : m_fenwick() { for( int j = 1 ; j <= N ; j++ ){ T& fenwick_j = m_fenwick[j]; int i = j - 1; fenwick_j = a[i]; int i_lim = j - ( j & -j ); while( i != i_lim ){ fenwick_j += m_fenwick[i]; i -= ( i & -i ); } } } template inline void BIT::Set( const int& i , const T& n ) { Add( i , n - IntervalSum( i , i ) ); } template inline BIT& BIT::operator+=( const T ( & a )[N] ) { for( int i = 0 ; i < N ; i++ ){ Add( i , a[i] ); } return *this; } template void BIT::Add( const int& i , const T& n ) { int j = i + 1; while( j <= N ){ m_fenwick[j] += n; j += ( j & -j ); } return; } template T BIT::InitialSegmentSum( const int& i_final ) const { T sum = 0; int j = ( i_final < N ? i_final : N - 1 ) + 1; while( j > 0 ){ sum += m_fenwick[j]; j -= j & -j; } return sum; } template inline T BIT::IntervalSum( const int& i_start , const int& i_final ) const { return InitialSegmentSum( i_final ) - InitialSegmentSum( i_start - 1 ); } // template // int BIT::BinarySearch( const T& n ) const // { // int j = 0; // int power = PowerCalculation.m_val; // T sum{}; // T sum_next{}; // while( power > 0 ){ // int j_next = j | power; // if( j_next < N ){ // sum_next += m_fenwick[j_next]; // if( sum_next < n ){ // sum = sum_next; // j = j_next; // } else { // sum_next = sum; // } // } // power >>= 1; // } // // InitialSegmentSum( i )がt未満となるiが存在するならばjはその最大値に1を足したものとなり、 // // InitialSegmentSum( i )がt未満となるiが存在しないならばj=0となり、 // // いずれの場合もjはInitialSegmentSum( i )がt以上となる最小のiと等しい。 // return j; // } // template inline int BIT::BinarySearch( const int& i_start , const T& n ) const { return max( i_start , BinarySearch( InitialSegmentSum( i_start ) + n ) ); } int main() { UNTIE; LIBRARY_SEARCH; CEXPR( int , bound_N , 100000 ); CIN_ASSERT( N , 1 , bound_N ); CIN_ASSERT( M , 0 , N ); CEXPR( ll , P , 998244353 ); static pair PK[bound_N]; static pair KP[bound_N]; static BIT bitP{}; FOR( m , 0 , M ){ CIN_ASSERT( Pi , 1 , N ); CIN_ASSERT( Ki , 1 , N ); Pi--; Ki--; PK[m] = pair( Pi , Ki ); KP[m] = pair( Ki , Pi ); bitP.Add( Pi , 1 ); } int max_index = max( N - M , 2 ); FACTORIAL_MOD( factorial , factorial_inv , inv , max_index , bound_N , P ); ll& factorial_N_M = factorial[N - M]; ll answer0 = ll( N - M ) * ( N - M - 1 ) / 2 % P * factorial_N_M % P * inv[2] % P; CERR( "answer0: " << ll( N - M ) * ( N - M - 1 ) / 2 << "," << factorial_N_M % P * inv[2] % P ); sort( PK , PK + M ); sort( KP , KP + M ); ll& factorial_N_M_1 = factorial[ max( N - M - 1 , 0 ) ]; ll answer1 = 0; FOR( i , 0 , M ){ pair& KPi = KP[i]; answer1 += ll( KPi.first - i ) * ( N - KPi.second - bitP.IntervalSum( KPi.second , N - 1 ) ); CERR( "answer1," << i << ": " << KPi.first << "," << KPi.second << "," << KPi.first - i << "," << N - KPi.second - bitP.IntervalSum( KPi.second , N - 1 ) << "," << factorial_N_M_1 ); } ( ( answer1 %= P ) *= factorial_N_M_1 ) %= P; ll answer2 = 0; FOREQINV( i , M - 1 , 0 ){ pair& KPi = KP[i]; answer2 += ll( N - KPi.first - M + i ) * ( KPi.second - bitP.IntervalSum( 0 , KPi.second - 1 ) ); CERR( "answer2," << i << ": " << KPi.first << "," << KPi.second << "," << N - KPi.first - M + i << "," << KPi.second - bitP.IntervalSum( 0 , KPi.second - 1 ) << "," << factorial_N_M_1 ); } ( ( answer2 %= P ) *= factorial_N_M_1 ) %= P; static BIT bitK{}; ll answer3 = 0; FOREQINV( i , M - 1 , 0 ){ pair& PKi = PK[i]; bitK.Add( PKi.second , 1 ); answer3 += bitK.IntervalSum( 0 , PKi.second - 1 ); CERR( "answer1," << i << ": " << PKi.first << "," << PKi.second << "," << bitK.IntervalSum( 0 , PKi.second - 1 ) << "," << factorial_N_M ); } ( answer3 *= factorial_N_M ) %= P; CERR( answer0 << "," << answer1 << "," << answer2 << "," << answer3 ); RETURN( ( answer0 + answer1 + answer2 + answer3 ) % P ); }