Contagem de ultrapassadores de cada elemento na matriz
Dado um array de inteiros distintos arr[] a superar de um elemento arr[i] é qualquer elemento arr[j] tal que j > i e arr[j] > arr[i]. Encontre o número de ultrapassadores para cada elemento da matriz.
Exemplos:
Entrada: arr[] = [2 7 5 3 8 1]
Saída: [4 1 1 1 0 0]
Explicação: Para 2 existem 4 elementos maiores à sua direita: [7 5 3 8]
Para 7 há 1 elemento maior à sua direita: [8]
Para 5 há 1 elemento maior à sua direita: [8]
Para 3 há 1 elemento maior à sua direita: [8]
Para 8 não há elemento maior à sua direita: [0]
Para 1 não há elemento maior à sua direita: [0]Entrada: arr[] = [4 5 1]
Saída: [1 0 0]
Explicação: Para 4 há 1 elemento maior à sua direita: [5]
Para 5 não há elemento maior à sua direita: [0]
Para 1 não há elemento maior à sua direita: [0]
Índice
- [Abordagem ingênua] - Usando dois loops aninhados - O(n^2) Tempo e O(1) Espaço
- [Abordagem esperada] - Usando a etapa de mesclagem de classificação de mesclagem - Tempo O (n Log n) e Espaço O (n)
[Abordagem ingênua] - Usando dois loops aninhados - O(n^2) Tempo e O(1) Espaço
A abordagem mais simples é iterar através da matriz e para cada elemento contar o número de elementos para seu certo aquilo é maior do que isso.
C++ #include #include using namespace std ; vector < int > findSurpasser ( vector < int > & arr ) { int n = arr . size (); // array to store surpasser counts vector < int > res ( n 0 ); for ( int i = 0 ; i < n ; i ++ ) { // Find surpasser for arr[i] int count = 0 ; for ( int j = i + 1 ; j < n ; j ++ ) { if ( arr [ j ] > arr [ i ]) count ++ ; } res [ i ] = count ; } return res ; } int main () { vector < int > arr = { 2 7 5 3 8 1 }; vector < int > res = findSurpasser ( arr ); for ( int count : res ) cout < < count < < ' ' ; return 0 ; }
C #include #include int * findSurpasser ( int arr [] int n ) { // Array to store surpasser counts int * res = ( int * ) malloc ( n * sizeof ( int )); for ( int i = 0 ; i < n ; i ++ ) { // Find surpasser for arr[i] int count = 0 ; for ( int j = i + 1 ; j < n ; j ++ ) { if ( arr [ j ] > arr [ i ]) count ++ ; } res [ i ] = count ; } return res ; } int main () { int arr [] = { 2 7 5 3 8 1 }; int n = sizeof ( arr ) / sizeof ( arr [ 0 ]); int * res = findSurpasser ( arr n ); for ( int i = 0 ; i < n ; i ++ ) printf ( '%d ' res [ i ]); return 0 ; }
Java import java.util.ArrayList ; class GfG { static ArrayList < Integer > findSurpasser ( int [] arr ) { int n = arr . length ; // List to store surpasser counts ArrayList < Integer > res = new ArrayList <> (); for ( int i = 0 ; i < n ; i ++ ) { // Find surpasser for arr[i] int count = 0 ; for ( int j = i + 1 ; j < n ; j ++ ) { if ( arr [ j ] > arr [ i ] ) count ++ ; } res . add ( count ); } return res ; } public static void main ( String [] args ) { int [] arr = { 2 7 5 3 8 1 }; ArrayList < Integer > res = findSurpasser ( arr ); for ( int count : res ) System . out . print ( count + ' ' ); } }
Python def findSurpasser ( arr ): n = len ( arr ) # List to store surpasser counts res = [ 0 ] * n for i in range ( n ): # Find surpasser for arr[i] count = 0 for j in range ( i + 1 n ): if arr [ j ] > arr [ i ]: count += 1 res [ i ] = count return res if __name__ == '__main__' : arr = [ 2 7 5 3 8 1 ] result = findSurpasser ( arr ) for val in result : print ( val end = ' ' )
C# using System ; using System.Collections.Generic ; class GfG { static List < int > findSurpasser ( int [] arr ) { int n = arr . Length ; // List to store surpasser counts List < int > res = new List < int > (); for ( int i = 0 ; i < n ; i ++ ) { // Find surpasser for arr[i] int count = 0 ; for ( int j = i + 1 ; j < n ; j ++ ) { if ( arr [ j ] > arr [ i ]) count ++ ; } res . Add ( count ); } return res ; } static void Main ( string [] args ) { int [] arr = { 2 7 5 3 8 1 }; List < int > result = findSurpasser ( arr ); foreach ( int count in result ) Console . Write ( count + ' ' ); } }
JavaScript function findSurpasser ( arr ) { const n = arr . length ; // array to store surpasser counts let res = new Array ( n ). fill ( 0 ); for ( let i = 0 ; i < n ; i ++ ) { // Find surpasser for arr[i] let count = 0 ; for ( let j = i + 1 ; j < n ; j ++ ) { if ( arr [ j ] > arr [ i ]) count ++ ; } res [ i ] = count ; } return res ; } // Driver Code const arr = [ 2 7 5 3 8 1 ]; const result = findSurpasser ( arr ); console . log ( result . join ( ' ' ));
Saída
4 1 1 1 0 0
[Abordagem esperada] - Usando a etapa de mesclagem da classificação de mesclagem - Tempo O (n Log n) e Espaço O (n)
Nesta abordagem usamos o etapa de mesclagem de Caminhadas . Durante a fusão, se o com elemento na metade esquerda é menor do que o jº elemento na metade direita significa que todos restante elementos na metade direita (de j ao final) são maior do que o com elemento na metade esquerda (já que ambas as metades são classificado ). Portanto, somamos o número de elementos restantes na metade direita para o superar a contagem do com elemento da metade esquerda. Este processo é repetido para todos os elementos da metade esquerda à medida que são mesclados com a metade direita.
Como todos os elementos do array são distinto usamos um mapa hash para manter armazenado a contagem de ultrapassadores para cada elemento. Após a conclusão da classificação por mesclagem, preenchemos a matriz de resultados com as contagens de ultrapassadores, mantendo a mesma ordem da entrada original.
C++ #include #include #include using namespace std ; // Merge function to sort the array and update surpasser counts int merge ( vector < int > & arr int lo int mid int hi unordered_map < int int > & m ) { int n1 = mid - lo + 1 ; int n2 = hi - mid ; vector < int > left ( n1 ) right ( n2 ); // Copy data into temporary arrays left[] and right[] for ( int i = 0 ; i < n1 ; i ++ ) left [ i ] = arr [ lo + i ]; for ( int j = 0 ; j < n2 ; j ++ ) right [ j ] = arr [ mid + 1 + j ]; int i = 0 j = 0 k = lo ; // Merging two halves while ( i < n1 && j < n2 ) { // All elements in right[j..n2] are greater than left[i] // So add n2 - j in surpasser count of left[i] if ( left [ i ] < right [ j ]) { m [ left [ i ]] += n2 - j ; arr [ k ++ ] = left [ i ++ ]; } else { arr [ k ++ ] = right [ j ++ ]; } } // Copy remaining elements of left[] if any while ( i < n1 ) arr [ k ++ ] = left [ i ++ ]; // Copy remaining elements of right[] if any while ( j < n2 ) arr [ k ++ ] = right [ j ++ ]; } void mergeSort ( vector < int > & arr int lo int hi unordered_map < int int > & m ) { if ( lo < hi ) { int mid = lo + ( hi - lo ) / 2 ; // Sort left and right half mergeSort ( arr lo mid m ); mergeSort ( arr mid + 1 hi m ); // Merge them merge ( arr lo mid hi m ); } } vector < int > findSurpasser ( vector < int >& arr ) { int n = arr . size (); // Map to store surpasser counts unordered_map < int int > m ; // Duplicate array to perform merge Sort // so that orginial array is not modified vector < int > dup = arr ; mergeSort ( dup 0 n - 1 m ); // Store surpasser counts in result array // in the same order as given array vector < int > res ( n ); for ( int i = 0 ; i < n ; i ++ ) res [ i ] = m [ arr [ i ]]; return res ; } int main () { vector < int > arr = { 2 7 5 3 8 1 }; vector < int > res = findSurpasser ( arr ); for ( int count : res ) cout < < count < < ' ' ; return 0 ; }
Java import java.util.List ; import java.util.Map ; import java.util.HashMap ; import java.util.ArrayList ; class GfG { // Merge function to sort the array // and update surpasser counts static void merge ( int [] arr int lo int mid int hi Map < Integer Integer > m ) { int n1 = mid - lo + 1 ; int n2 = hi - mid ; int [] left = new int [ n1 ] ; int [] right = new int [ n2 ] ; // Copy data into temporary arrays left[] and right[] for ( int i = 0 ; i < n1 ; i ++ ) left [ i ] = arr [ lo + i ] ; for ( int j = 0 ; j < n2 ; j ++ ) right [ j ] = arr [ mid + 1 + j ] ; int i = 0 j = 0 k = lo ; // Merging two halves while ( i < n1 && j < n2 ) { // All elements in right[j..n2] are greater than left[i] // So add n2 - j to surpasser count of left[i] if ( left [ i ] < right [ j ] ) { m . put ( left [ i ] m . getOrDefault ( left [ i ] 0 ) + n2 - j ); arr [ k ++] = left [ i ++] ; } else { arr [ k ++] = right [ j ++] ; } } // Copy remaining elements of left[] if any while ( i < n1 ) arr [ k ++] = left [ i ++] ; // Copy remaining elements of right[] if any while ( j < n2 ) arr [ k ++] = right [ j ++] ; } static void mergeSort ( int [] arr int lo int hi Map < Integer Integer > m ) { if ( lo < hi ) { int mid = lo + ( hi - lo ) / 2 ; // Sort left and right halves mergeSort ( arr lo mid m ); mergeSort ( arr mid + 1 hi m ); // Merge them merge ( arr lo mid hi m ); } } static ArrayList < Integer > findSurpasser ( int [] arr ) { int n = arr . length ; // Map to store surpasser counts Map < Integer Integer > m = new HashMap <> (); // Duplicate array to perform merge sort int [] dup = arr . clone (); mergeSort ( dup 0 n - 1 m ); // Store surpasser counts in result list ArrayList < Integer > res = new ArrayList <> (); for ( int i = 0 ; i < n ; i ++ ) res . add ( m . getOrDefault ( arr [ i ] 0 )); return res ; } public static void main ( String [] args ) { int [] arr = { 2 7 5 3 8 1 }; ArrayList < Integer > res = findSurpasser ( arr ); for ( int count : res ) System . out . print ( count + ' ' ); } }
Python def merge ( arr lo mid hi m ): n1 = mid - lo + 1 n2 = hi - mid left = arr [ lo : lo + n1 ] right = arr [ mid + 1 : mid + 1 + n2 ] i = j = 0 k = lo # Merging two halves while i < n1 and j < n2 : # All elements in right[j..n2] are greater than left[i] # So add n2 - j in surpasser count of left[i] if left [ i ] < right [ j ]: m [ left [ i ]] += n2 - j arr [ k ] = left [ i ] i += 1 else : arr [ k ] = right [ j ] j += 1 k += 1 # Copy remaining elements of left[] if any while i < n1 : arr [ k ] = left [ i ] i += 1 k += 1 # Copy remaining elements of right[] if any while j < n2 : arr [ k ] = right [ j ] j += 1 k += 1 def mergeSort ( arr lo hi m ): if lo < hi : mid = lo + ( hi - lo ) // 2 # Sort left and right half mergeSort ( arr lo mid m ) mergeSort ( arr mid + 1 hi m ) # Merge them merge ( arr lo mid hi m ) def findSurpasser ( arr ): n = len ( arr ) # Map to store surpasser counts m = { key : 0 for key in arr } # Duplicate array to perform merge Sort # so that original array is not modified dup = arr [:] mergeSort ( dup 0 n - 1 m ) # Store surpasser counts in result array # in the same order as given array res = [ m [ arr [ i ]] for i in range ( n )] return res if __name__ == '__main__' : arr = [ 2 7 5 3 8 1 ] result = findSurpasser ( arr ) for val in result : print ( val end = ' ' )
C# using System ; using System.Collections.Generic ; class GfG { // Merge function to sort the array // and update surpasser counts static void merge ( int [] arr int lo int mid int hi Dictionary < int int > m ) { int n1 = mid - lo + 1 ; int n2 = hi - mid ; int [] left = new int [ n1 ]; int [] right = new int [ n2 ]; // Copy data into temporary arrays for ( int i = 0 ; i < n1 ; i ++ ) left [ i ] = arr [ lo + i ]; for ( int j = 0 ; j < n2 ; j ++ ) right [ j ] = arr [ mid + 1 + j ]; int i1 = 0 j1 = 0 k = lo ; // Merge the two halves while ( i1 < n1 && j1 < n2 ) { // Count surpassers if ( left [ i1 ] < right [ j1 ]) { if ( ! m . ContainsKey ( left [ i1 ])) m [ left [ i1 ]] = 0 ; m [ left [ i1 ]] += n2 - j1 ; arr [ k ++ ] = left [ i1 ++ ]; } else { arr [ k ++ ] = right [ j1 ++ ]; } } // Copy remaining elements while ( i1 < n1 ) arr [ k ++ ] = left [ i1 ++ ]; while ( j1 < n2 ) arr [ k ++ ] = right [ j1 ++ ]; } static void mergeSort ( int [] arr int lo int hi Dictionary < int int > m ) { if ( lo < hi ) { int mid = lo + ( hi - lo ) / 2 ; // Recursive sort mergeSort ( arr lo mid m ); mergeSort ( arr mid + 1 hi m ); // Merge sorted halves merge ( arr lo mid hi m ); } } static List < int > findSurpasser ( int [] arr ) { int n = arr . Length ; Dictionary < int int > m = new Dictionary < int int > (); int [] dup = new int [ n ]; Array . Copy ( arr dup n ); mergeSort ( dup 0 n - 1 m ); List < int > res = new List < int > (); for ( int i = 0 ; i < n ; i ++ ) { res . Add ( m . ContainsKey ( arr [ i ]) ? m [ arr [ i ]] : 0 ); } return res ; } static void Main () { int [] arr = { 2 7 5 3 8 1 }; List < int > res = findSurpasser ( arr ); foreach ( int count in res ) Console . Write ( count + ' ' ); } }
JavaScript function merge ( arr lo mid hi m ) { const n1 = mid - lo + 1 ; const n2 = hi - mid ; const left = []; const right = []; // Copy data into temporary arrays left[] and right[] for ( let i = 0 ; i < n1 ; i ++ ) left [ i ] = arr [ lo + i ]; for ( let j = 0 ; j < n2 ; j ++ ) right [ j ] = arr [ mid + 1 + j ]; let i = 0 j = 0 k = lo ; // Merging two halves while ( i < n1 && j < n2 ) { // All elements in right[j..n2] are greater than left[i] // So add n2 - j in surpasser count of left[i] if ( left [ i ] < right [ j ]) { m [ left [ i ]] = ( m [ left [ i ]] || 0 ) + n2 - j ; arr [ k ++ ] = left [ i ++ ]; } else { arr [ k ++ ] = right [ j ++ ]; } } // Copy remaining elements of left[] if any while ( i < n1 ) arr [ k ++ ] = left [ i ++ ]; // Copy remaining elements of right[] if any while ( j < n2 ) arr [ k ++ ] = right [ j ++ ]; } function mergeSort ( arr lo hi m ) { if ( lo < hi ) { const mid = Math . floor ( lo + ( hi - lo ) / 2 ); // Sort left and right half mergeSort ( arr lo mid m ); mergeSort ( arr mid + 1 hi m ); // Merge them merge ( arr lo mid hi m ); } } function findSurpasser ( arr ) { const n = arr . length ; // Map to store surpasser counts const m = {}; // Duplicate array to perform merge Sort // so that original array is not modified const dup = arr . slice (); mergeSort ( dup 0 n - 1 m ); // Store surpasser counts in result array // in the same order as given array const res = []; for ( let i = 0 ; i < n ; i ++ ) res . push ( m [ arr [ i ]] || 0 ); return res ; } // Driver Code const arr = [ 2 7 5 3 8 1 ]; const res = findSurpasser ( arr ); console . log ( res . join ( ' ' ));
Saída
4 1 1 1 0 0
Artigos relacionados:
- Contagem de inversão
- Caminhadas
