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Count the number of occurrences of N in the array A

Zed Championship answered on April 21, 2022 Popularity 9/10 Helpfulness 1/10

answer Count the number of occurrences of N in the array A

related Count the occurrences of an element in an array

Count the number of occurrences of N in the array A

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# include <stdio.h> 
  
/* if x is present in arr[] then returns  
   the index of FIRST occurrence  
   of x in arr[0..n-1], otherwise returns -1 */
int first(int arr[], int low, int high, int x, int n) 
{ 
  if(high >= low) 
  { 
    int mid = (low + high)/2;  /*low + (high - low)/2;*/
    if( ( mid == 0 || x > arr[mid-1]) && arr[mid] == x) 
      return mid; 
    else if(x > arr[mid]) 
      return first(arr, (mid + 1), high, x, n); 
    else
      return first(arr, low, (mid -1), x, n); 
  } 
  return -1; 
} 
  
/* if x is present in arr[] then returns the 
   index of LAST occurrence of x in arr[0..n-1],  
   otherwise returns -1 */ 
int last(int arr[], int low, int high, int x, int n) 
{ 
  if (high >= low) 
  { 
    int mid = (low + high)/2;  /*low + (high - low)/2;*/
    if( ( mid == n-1 || x < arr[mid+1]) && arr[mid] == x ) 
      return mid; 
    else if(x < arr[mid]) 
      return last(arr, low, (mid -1), x, n); 
    else
      return last(arr, (mid + 1), high, x, n);       
  } 
  return -1; 
} 
  
/* if x is present in arr[] then returns the count 
   of occurrences of x, otherwise returns -1. */
int count(int arr[], int x, int n) 
{ 
  int i; // index of first occurrence of x in arr[0..n-1] 
  int j; // index of last occurrence of x in arr[0..n-1] 
      
  /* get the index of first occurrence of x */
  i = first(arr, 0, n-1, x, n); 
  
  /* If x doesn't exist in arr[] then return -1 */
  if(i == -1) 
    return i; 
     
  /* Else get the index of last occurrence of x.  
     Note that we are only looking in the subarray  
     after first occurrence */   
  j = last(arr, i, n-1, x, n);      
     
  /* return count */
  return j-i+1; 
} 
  
/* driver program to test above functions */
int main() 
{ 
  int arr[] = {1, 2, 2, 3, 3, 3, 3}; 
  int x =  3;  // Element to be counted in arr[] 
  int n = sizeof(arr)/sizeof(arr[0]); 
  int c = count(arr, x, n); 
  printf(" %d occurs %d times ", x, c); 
  getchar(); 
  return 0; 
}

Popularity 9/10 Helpfulness 1/10 Language whatever

Source: tutorialspoint.dev

Tags: count n whatever

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Contributed on Apr 21 2022

Zed Championship

0 Answers Avg Quality 2/10

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Count the occurrences of an element in an array

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array.filter(x => x === element).length

Popularity 8/10 Helpfulness 4/10 Language javascript

Source: dev.to

Tags: count element

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Contributed on Jan 29 2023

Poised Peacock

0 Answers Avg Quality 2/10

Count the number of occurrences of N in the array A

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Count the number of occurrences of N in the array A

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Count the occurrences of an element in an array

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