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Sort elements by frequency

Here given code implementation process.

//C Program 
//Sort elements by frequency
#include <stdio.h>

//Combine array elements by occurrence sequence
void arrange(int arr[],int size,int index,int *counter)
{
    if(index<0) return;
    
    int data=arr[index];

    arrange(arr,size,index-1,counter);


    for (int i = *counter; i < size && *counter<size ; ++i)
    {
      if(arr[i]==data )
      {
        //swap element value
        arr[i]=arr[*counter];
        arr[*counter]=data;
        (*counter)=*counter+1;
      }

    }
}

void sort_by_frequency(int arr[],int size)
{
  
  int sets=1,length=0;

  for (int i = 0; i < size-1; ++i)
  {
    //Get the unique element
    if(arr[i] != arr[i+1])
    {
      sets++;
    }
  }
  //Check that unique elements are more than one or not
  if(sets > 1)
  {
    //Create a new memory to store frequency of element
    int record[sets][2];

    int counter = 0;

    for (int i = 0; i < size-1; ++i)
    { 
      length++;

      if(arr[i] != arr[i+1])
      {
        //Assign value of array
        record[counter][0] = arr[i];

        //Assign value of element frequency
        record[counter][1] = length;

        //Reset the value of new element frequency is to zero
        length = 0;

        //modified index of record array
        counter++;
      }
     
    }
    
    if(record[counter-1][0] != arr[size-1])
    {
      //Get the frequency of last element
      record[counter][0]=arr[size-1];

      record[counter][1]=1;
    }

    length=0;

    for (int i = 0; i < sets; ++i)
    {
      counter = i;
      for (int j = 0; j < sets; ++j)
      {
        if(record[counter][1]<record[j][1])
        {
          counter=j;
        }
      }
      //Update actual array
      for (int k = 0; k < record[counter][1]; ++k,++length)
      {
        arr[length]=record[counter][0];

      }
      //set frequency is -1
      record[counter][1]=-1;
       
    }


    printf("\n");
  }
  
}
//print array elements
void print_array(int arr[],int size)
{  
  printf("\n");
  for(int i=0;i<size;i++)
  {
    printf("%3d",arr[i] );
  }
}
void sort_array(int arr[],int size)
{
  int counter=1;

  print_array(arr,size);

  arrange(arr,size,size-1,&counter);
 
  sort_by_frequency(arr,size);
  
  print_array(arr,size);
}

int main()
{
   
    //define array elements
    int arr[] = {6, 5, 4, 1, 6, 5, 5, 2, 9, 3, 1, 2, 2, 2 };
    
    //Get the size of array
    int size=(sizeof(arr)/sizeof(arr[0]));

    sort_array(arr,size);
    
   
   
    return 0;
}

Output

  6  5  4  1  6  5  5  2  9  3  1  2  2  2

  2  2  2  2  5  5  5  6  6  1  1  4  9  3
#include<iostream>

using namespace std;
/*
 C++ Program
 Sort elements by frequency
*/
class MyNumber {
  public:
    int counter;
  MyNumber() {
    this->counter = 0;
  }
  //Combine array elements by occurrence sequence
  void arrange(int arr[], int size, int index) {
    if (index < 0) {
      return;
    }
    int data = arr[index];
    this->arrange(arr, size, index - 1);
    for (int i = this->counter; i < size && this->counter < size; ++i) {
      if (arr[i] == data) {
        //swap element value
        arr[i] = arr[this->counter];
        arr[this->counter] = data;
        this->counter = this->counter + 1;
      }
    }
  }
  void sort_by_frequency(int arr[], int size) {
    int sets = 1, length = 0;
    for (int i = 0; i < size - 1; ++i) {
      //Get the unique element

      if (arr[i] != arr[i + 1]) {
        sets++;
      }
    }
    //Check that unique elements are more than one or not

    if (sets > 1) {
      //Create a new memory to store frequency of element
      int record[sets][2];
      int location = 0;
      for (int i = 0; i < size - 1; ++i) {
        length++;
        if (arr[i] != arr[i + 1]) {
          //Assign value of array
          record[location][0] = arr[i];
          //Assign value of element frequency
          record[location][1] = length;
          //Reset the value of new element frequency is to zero
          length = 0;
          //modified index of record array
          location++;
        }
      }
      if (record[location - 1][0] != arr[size - 1]) {
        //Get the frequency of last element
        record[location][0] = arr[size - 1];
        record[location][1] = 1;
      }
      length = 0;
      for (int i = 0; i < sets; ++i) {
        location = i;
        for (int j = 0; j < sets; ++j) {
          if (record[location][1] < record[j][1]) {
            location = j;
          }
        }
        //Update actual array

        for (int k = 0; k < record[location][1]; ++k, ++length) {
          arr[length] = record[location][0];
        }
        //set frequency is -1
        record[location][1] = -1;
      }
      cout << "\n";
    }
  }
  //print array elements
  void print_array(int arr[], int size) {
    cout << "\n";
    for (int i = 0; i < size; i++) {
      cout << " " << arr[i];
    }
  }
  void sort_array(int arr[], int size) {
    this->counter = 1;
    this->print_array(arr, size);
    this->arrange(arr, size, size - 1);
    this->sort_by_frequency(arr, size);
    this->print_array(arr, size);
  }
};
int main() {
  MyNumber obj ;
  int arr[] ={6, 5, 4, 1, 6, 5, 5, 2, 9, 3, 1, 2, 2, 2 };
  //Get the size of array
  int size = sizeof(arr) / sizeof(arr[0]);
  obj.sort_array(arr, size);
  return 0;
}

Output

 6 5 4 1 6 5 5 2 9 3 1 2 2 2

 2 2 2 2 5 5 5 6 6 1 1 4 9 3
/*
  Java Program
  Sort elements by frequency
*/
public class MyNumber {

  public int counter;
  public MyNumber()
  {
    counter=0;
  }
  //Combine array elements by occurrence sequence
  public void arrange(int []arr,int size,int index)
  {
      if(index < 0) {
       
        return;
      }
      
      int data = arr[index];

      arrange(arr,size,index-1);


      for (int i = counter; i < size && counter < size ; ++i)
      {
        if(arr[i]==data )
        {
          //swap element value
          arr[i] = arr[counter];
          arr[counter] = data;
          counter = counter+1;
        }

      }
  }

  public void sort_by_frequency(int []arr,int size)
  {
    
    int sets=1,length=0;

    for (int i = 0; i < size-1; ++i)
    {
      //Get the unique element
      if(arr[i] != arr[i+1])
      {
        sets++;
      }
    }
    //Check that unique elements are more than one or not
    if(sets > 1)
    {
      //Create a new memory to store frequency of element
      int [][]record = new int[sets][2];

      int location = 0;

      for (int i = 0; i < size-1; ++i)
      { 
        length++;

        if(arr[i] != arr[i+1])
        {
          //Assign value of array
          record[location][0] = arr[i];

          //Assign value of element frequency
          record[location][1] = length;

          //Reset the value of new element frequency is to zero
          length = 0;

          //modified index of record array
          location++;
        }
       
      }
      
      if(record[location-1][0] != arr[size-1])
      {
        //Get the frequency of last element
        record[location][0]=arr[size-1];

        record[location][1]=1;
      }

      length=0;

      for (int i = 0; i < sets; ++i)
      {
        location = i;
        for (int j = 0; j < sets; ++j)
        {
          if(record[location][1]<record[j][1])
          {
            location=j;
          }
        }
        //Update actual array
        for (int k = 0; k < record[location][1]; ++k,++length)
        {
          arr[length]=record[location][0];

        }
        //set frequency is -1
        record[location][1]=-1;
         
      }


      System.out.print("\n");
    }
    
  }
  //print array elements
  public void print_array(int []arr,int size)
  {  
    System.out.print("\n");
    for(int i=0;i<size;i++)
    {
      System.out.print(" "+arr[i] );
    }
  }
  public void sort_array(int []arr,int size)
  {
    counter=1;

    print_array(arr,size);

    arrange(arr,size,size-1);
   
    sort_by_frequency(arr,size);
    
    print_array(arr,size);
  }
  public static void main(String[] args) {

    MyNumber obj = new MyNumber();
    

    int []arr = { 6, 5, 4, 1, 6, 3, 5, 5, 2, 9, 3, 1, 2, 2, 2 };

    //Get the size of array
    int size = arr.length;

    obj.sort_array(arr,size);
  }
}

Output

 6 5 4 1 6 5 5 2 9 3 1 2 2 2

 2 2 2 2 5 5 5 6 6 1 1 4 9 3
/*
  C# Program
  Sort elements by frequency
*/
using System;
public class MyNumber {

	public int counter;
	public MyNumber() {
		counter = 0;
	}
	//Combine array elements by occurrence sequence
	public void arrange(int[] arr, int size, int index) {
		if (index < 0) {

			return;
		}

		int data = arr[index];

		arrange(arr, size, index - 1);


		for (int i = counter; i < size && counter < size; ++i) {
			if (arr[i] == data) {
				//swap element value
				arr[i] = arr[counter];
				arr[counter] = data;
				counter = counter + 1;
			}

		}
	}

	public void sort_by_frequency(int[] arr, int size) {

		int sets = 1,length = 0;

		for (int i = 0; i < size - 1; ++i) {
			//Get the unique element
			if (arr[i] != arr[i + 1]) {
				sets++;
			}
		}
		//Check that unique elements are more than one or not
		if (sets > 1) {
			//Create a new memory to store frequency of element
			int[,] record = new int[sets,2];

			int location = 0;

			for (int i = 0; i < size - 1; ++i) {
			length++;

				if (arr[i] != arr[i + 1]) {
					//Assign value of array
					record[location,0] = arr[i];

					//Assign value of element frequency
					record[location,1] =length;

					//Reset the value of new element frequency is to zero
					length = 0;

					//modified index of record array
					location++;
				}

			}

			if (record[location - 1,0] != arr[size - 1]) {
				//Get the frequency of last element
				record[location,0] = arr[size - 1];

				record[location,1] = 1;
			}

		length = 0;

			for (int i = 0; i < sets; ++i) {
				location = i;
				for (int j = 0; j < sets; ++j) {
					if (record[location,1] < record[j,1]) {
						location = j;
					}
				}
				//Update actual array
				for (int k = 0; k < record[location,1]; ++k, ++length) {
					arr[length] = record[location,0];

				}
				//set frequency is -1
				record[location,1] = -1;

			}


			Console.Write("\n");
		}

	}
	//print array elements
	public void print_array(int[] arr, int size) {
		Console.Write("\n");
		for (int i = 0; i < size; i++) {
			Console.Write(" " + arr[i]);
		}
	}
	public void sort_array(int[] arr, int size) {
		counter = 1;

		print_array(arr, size);

		arrange(arr, size, size - 1);

		sort_by_frequency(arr, size);

		print_array(arr, size);
	}
	public static void Main(String[] args) {

		MyNumber obj = new MyNumber();


		int []arr = {
			6,
			5,
			4,
			1,
			6,
			3,
			5,
			5,
			2,
			9,
			3,
			1,
			2,
			2,
			2
		};

		//Get the size of array
		int size = arr.Length;

		obj.sort_array(arr, size);
	}
}

Output

 6 5 4 1 6 3 5 5 2 9 3 1 2 2 2

 2 2 2 2 5 5 5 6 6 1 1 3 3 4 9
# Python 3 Program
# Sort elements by frequency
class MyNumber :
  
  def __init__(self) :
    self.counter = 0
  
  # Combine array elements by occurrence sequence
  def arrange(self, arr, size, index) :
    if (index < 0) :
      return
    
    data = arr[index]
    self.arrange(arr, size, index - 1)
    i = self.counter
    while (i < size and self.counter < size) :
      if (arr[i] == data) :
        # swap element value
        arr[i] = arr[self.counter]
        arr[self.counter] = data
        self.counter = self.counter + 1
      
      i += 1
    
  
  def sort_by_frequency(self, arr, size) :
    sets = 1
    length = 0
    i = 0
    j = 0
    k = 0
    while (i < size - 1) :
      # Get the unique element

      if (arr[i] != arr[i + 1]) :
        sets += 1
      
      i += 1
    
    # Check that unique elements are more than one or not

    if (sets > 1) :
      record = [ [0] * 2 for _ in range(sets)]
      location = 0
      i = 0
      while (i < size - 1) :
        length += 1
        if (arr[i] != arr[i + 1]) :
          # Assign value of array
          record[location][0] = arr[i]
          # Assign value of element frequency
          record[location][1] = length
          # Reset the value of new element frequency is to zero
          length = 0
          # modified index of record array
          location += 1
        
        i += 1
      
      if (record[location - 1][0] != arr[size - 1]) :
        # Get the frequency of last element
        record[location][0] = arr[size - 1]
        record[location][1] = 1
      
      length = 0
      i = 0
      while (i < sets) :
        location = i
        j = 0
        while (j < sets) :
          if (record[location][1] < record[j][1]) :
            location = j
          
          j += 1
        
        # Update actual array
        k = 0
        while (k < record[location][1]) :
          arr[length] = record[location][0]
          k += 1
          length += 1
        
        # set frequency is -1
        record[location][1] = -1
        i += 1
      
      print("\n")
    
  
  # print array elements
  def print_array(self, arr, size) :
    print(end="\n")
    i = 0
    while (i < size) :
      print(" ", arr[i],end="")
      i += 1
    
  
  def sort_array(self, arr, size) :
    self.counter = 1
    self.print_array(arr, size)
    self.arrange(arr, size, size - 1)
    self.sort_by_frequency(arr, size)
    self.print_array(arr, size)
  

def main() :
  obj = MyNumber()
  arr = [6, 5, 4, 1, 6, 3, 5, 5, 2, 9, 3, 1, 2, 2, 2]
  size = len(arr)
  obj.sort_array(arr, size)


if __name__ == "__main__":
  main()

Output

 6 5 4 1 6 3 5 5 2 9 3 1 2 2 2

 2 2 2 2 5 5 5 6 6 1 1 3 3 4 9
# Ruby Program 
# Sort elements by frequency
class MyNumber 
	# Define the accessor and reader of class MyNumber
    attr_reader :counter
    attr_accessor :counter
	def initialize() 
		@counter = 0
	end
	# Combine array elements by occurrence sequence
	def arrange(arr, size, index) 
		if (index < 0) 
			return
		end
		data = arr[index]
		self.arrange(arr, size, index - 1)
		i = @counter
		while (i < size and @counter < size) 
			if (arr[i] == data) 
				# swap element value
				arr[i] = arr[@counter]
				arr[@counter] = data
				@counter = @counter + 1
			end
			i += 1
		end
	end
	def sort_by_frequency(arr, size) 
		sets = 1
		length = 0
		i = 0
		j = 0
		k = 0
		while (i < size - 1) 
			# Get the unique element

			if (arr[i] != arr[i + 1]) 
				sets += 1
			end
			i += 1
		end
		# Check that unique elements are more than one or not

		if (sets > 1) 
			record = Array.new(sets){Array.new(2,0)}
			location = 0
			i = 0
			while (i < size - 1) 
				length += 1
				if (arr[i] != arr[i + 1]) 
					# Assign value of array
					record[location][0] = arr[i]
					# Assign value of element frequency
					record[location][1] = length
					# Reset the value of new element frequency is to zero
					length = 0
					# modified index of record array
					location += 1
				end
				i += 1
			end
			if (record[location - 1][0] != arr[size - 1]) 
				# Get the frequency of last element
				record[location][0] = arr[size - 1]
				record[location][1] = 1
			end
			length = 0
			i = 0
			while (i < sets) 
				location = i
				j = 0
				while (j < sets) 
					if (record[location][1] < record[j][1]) 
						location = j
					end
					j += 1
				end
				# Update actual array
				k = 0
				while (k < record[location][1]) 
					arr[length] = record[location][0]
					k += 1
					length += 1
				end
				# set frequency is -1
				record[location][1] = -1
				i += 1
			end
			print("\n")
		end
	end
	# print array elements
	def print_array(arr, size) 
		print("\n")
		i = 0
		while (i < size) 
			print(" ", arr[i])
			i += 1
		end
	end
	def sort_array(arr, size) 
		@counter = 1
		self.print_array(arr, size)
		self.arrange(arr, size, size - 1)
		self.sort_by_frequency(arr, size)
		self.print_array(arr, size)
	end
end
def main() 
	obj = MyNumber.new()
	arr = [6, 5, 4, 1, 6, 3, 5, 5, 2, 9, 3, 1, 2, 2, 2]
	size = arr.length
	obj.sort_array(arr, size)
end


main()

Output

 6 5 4 1 6 3 5 5 2 9 3 1 2 2 2

 2 2 2 2 5 5 5 6 6 1 1 3 3 4 9
/*
 Scala Program
 Sort elements by frequency
*/
class MyNumber (var counter: Int){

	def this() {
		this(0);
	}
	//Combine array elements by occurrence sequence
	def arrange(arr: Array[Int], size: Int, index: Int): Unit = {
		if (index < 0) {
			return;
		}
		var data: Int = arr(index);
		this.arrange(arr, size, index - 1);
		var i: Int = this.counter;
		while (i < size && this.counter < size) {
			if (arr(i) == data) {
				//swap element value
				arr(i) = arr(this.counter);
				arr(this.counter) = data;
				this.counter = this.counter + 1;
			}
			i += 1;
		}
	}
	def sort_by_frequency(arr: Array[Int], size: Int): Unit = {
		var sets: Int = 1;
		
		var length: Int = 0;
		var i: Int = 0;
		var j: Int = 0;
		var k: Int = 0;
		while (i < size - 1) {
			//Get the unique element

			if (arr(i) != arr(i + 1)) {
				sets += 1;
			}
			i += 1;
		}
		//Check that unique elements are more than one or not

		if (sets > 1) {
			var record: Array[Array[Int]] = Array.fill[Int](sets,2)(0);
			var location: Int = 0;
			i = 0;
			while (i < size - 1) {
				length += 1;
				if (arr(i) != arr(i + 1)) {
					//Assign value of array
					record(location)(0) = arr(i);
					//Assign value of element frequency
					record(location)(1) = length;
					//Reset the value of new element frequency is to zero
					length = 0;
					//modified index of record array
					location += 1;
				}
				i += 1;
			}
			if (record(location - 1)(0) != arr(size - 1)) {
				//Get the frequency of last element
				record(location)(0) = arr(size - 1);
				record(location)(1) = 1;
			}
			length = 0;
			i = 0;
			while (i < sets) {
				location = i;
				j = 0;
				while (j < sets) {
					if (record(location)(1) < record(j)(1)) {
						location = j;
					}
					j += 1;
				}
				//Update actual array
				k = 0;
				while (k < record(location)(1)) {
					arr(length) = record(location)(0);
					k += 1;
					length += 1;
				}
				//set frequency is -1
				record(location)(1) = -1;
				i += 1;
			}
			print("\n");
		}
	}
	//print array elements
	def print_array(arr: Array[Int], size: Int): Unit = {
		print("\n");
		var i: Int = 0;
		while (i < size) {
			print(" " + arr(i));
			i += 1;
		}
	}
	def sort_array(arr: Array[Int], size: Int): Unit = {
		this.counter = 1;
        this.print_array(arr, size);
        this.arrange(arr, size, size - 1);
        this.sort_by_frequency(arr, size);
        this.print_array(arr, size);
	}
}
object Main {
	def main(args: Array[String]): Unit = {
		var obj: MyNumber = new MyNumber();
		var arr: Array[Int] = Array(6, 5, 4, 1, 6, 3, 5, 5, 2, 9, 3, 1, 2, 2, 2);
		var size: Int = arr.length;obj.sort_array(arr, size);
	}
}

Output

 6 5 4 1 6 3 5 5 2 9 3 1 2 2 2

 2 2 2 2 5 5 5 6 6 1 1 3 3 4 9
/*
  Swift 4 Program
  Sort elements by frequency
*/
class MyNumber {
	var counter : Int;
	init() {
		self.counter = 0;
	}
	//Combine array elements by occurrence sequence
	func arrange(_ arr: inout [Int], _ size: Int, _ index: Int) {
		if (index < 0) {
			return;
		}
		let data: Int = arr[index];
		self.arrange(&arr, size, index - 1);
		var i: Int = self.counter;
		while (i < size && self.counter < size) {
			if (arr[i] == data) {
				//swap element value
				arr[i] = arr[self.counter];
				arr[self.counter] = data;
				self.counter = self.counter + 1;
			}
			i += 1;
		}
	}
	func sort_by_frequency(_ arr: inout [Int], _ size: Int) {
		var sets: Int = 1;
		var length: Int = 0;
		var i: Int = 0;
		var j: Int = 0;
		var k: Int = 0;
		while (i < size - 1) {
			//Get the unique element

			if (arr[i] != arr[i + 1]) {
				sets += 1;
			}
			i += 1;
		}
		//Check that unique elements are more than one or not

		if (sets > 1) {
			var record: [[Int]] = Array( repeating : Array( repeating:0 , count:2) ,  count:sets);
                                                                     
			var location: Int = 0;
			i = 0;
			while (i < size - 1) {
				length += 1;
				if (arr[i] != arr[i + 1]) {
					//Assign value of array
					record[location][0] = arr[i];
					//Assign value of element frequency
					record[location][1] = length;
					//Reset the value of new element frequency is to zero
					length = 0;
					//modified index of record array
					location += 1;
				}
				i += 1;
			}
			if (record[location - 1][0] != arr[size - 1]) {
				//Get the frequency of last element
				record[location][0] = arr[size - 1];
				record[location][1] = 1;
			}
			length = 0;
			i = 0;
			while (i < sets) {
				location = i;
				j = 0;
				while (j < sets) {
					if (record[location][1] < record[j][1]) {
						location = j;
					}
					j += 1;
				}
				//Update actual array
				k = 0;
				while (k < record[location][1]) {
					arr[length] = record[location][0];
					k += 1;
					length += 1;
				}
				//set frequency is -1
				record[location][1] = -1;
				i += 1;
			}
			print(terminator:"\n");
		}
	}
	//print array elements
	func print_array(_ arr: [Int], _ size: Int) {
		print(terminator:"\n");
		var i: Int = 0;
		while (i < size) {
			print(" ", arr[i],terminator:"");
			i += 1;
		}
	}
	func sort_array(_ arr: inout [Int], _ size: Int) {
		self.counter = 1;
		self.print_array(arr, size);
		self.arrange(&arr, size, size - 1);
		self.sort_by_frequency(&arr, size);
		self.print_array(arr, size);
	}
}
func main() {
	let obj: MyNumber = MyNumber();
	var arr: [Int] = [6, 5, 4, 1, 6, 3, 5, 5, 2, 9, 3, 1, 2, 2, 2];
	let size: Int = arr.count;
	obj.sort_array(&arr, size);
}
main();

Output

  6  5  4  1  6  3  5  5  2  9  3  1  2  2  2

  2  2  2  2  5  5  5  6  6  1  1  3  3  4  9
/*
 Node Js Program
 Sort elements by frequency
*/
class MyNumber {
	
	constructor() {
		this.counter = 0;
	}
	//Combine array elements by occurrence sequence
	arrange(arr, size, index) {
		if (index < 0) {
			return;
		}
		var data = arr[index];
		this.arrange(arr, size, index - 1);
		for (var i = this.counter; i < size && this.counter < size; ++i) {
			if (arr[i] == data) {
				//swap element value
				arr[i] = arr[this.counter];
				arr[this.counter] = data;
				this.counter = this.counter + 1;
			}
		}
	}
	sort_by_frequency(arr, size) {
		var sets = 1;
		var length = 0;
		for (var i = 0; i < size - 1; ++i) {
			//Get the unique element

			if (arr[i] != arr[i + 1]) {
				sets++;
			}
		}
		//Check that unique elements are more than one or not

		if (sets > 1) {
			//Create a new memory to store frequency of element
			var record = Array(sets).fill(0).map(() => new Array(2).fill(0));;
			var location = 0;
			for (var i = 0; i < size - 1; ++i) {
				length++;
				if (arr[i] != arr[i + 1]) {
					//Assign value of array
					record[location][0] = arr[i];
					//Assign value of element frequency
					record[location][1] = length;
					//Reset the value of new element frequency is to zero
					length = 0;
					//modified index of record array
					location++;
				}
			}
			if (record[location - 1][0] != arr[size - 1]) {
				//Get the frequency of last element
				record[location][0] = arr[size - 1];
				record[location][1] = 1;
			}
			length = 0;
			for (var i = 0; i < sets; ++i) {
				location = i;
				for (var j = 0; j < sets; ++j) {
					if (record[location][1] < record[j][1]) {
						location = j;
					}
				}
				//Update actual array

				for (var k = 0; k < record[location][1]; ++k,
					++length) {
					arr[length] = record[location][0];
				}
				//set frequency is -1
				record[location][1] = -1;
			}
			process.stdout.write("\n");
		}
	}
	//print array elements
	print_array(arr, size) {
		process.stdout.write("\n");
		for (var i = 0; i < size; i++) {
			process.stdout.write(" " + arr[i]);
		}
	}
	sort_array(arr, size) {
		this.counter = 1;
		this.print_array(arr, size);
		this.arrange(arr, size, size - 1);
		this.sort_by_frequency(arr, size);
		this.print_array(arr, size);
	}
}

function main(args) {
	var obj = new MyNumber();
	var arr = [6, 5, 4, 1, 6, 3, 5, 5, 2, 9, 3, 1, 2, 2, 2];
	//Get the size of array
	var size = arr.length;
	obj.sort_array(arr, size);
}
main();

Output

 6 5 4 1 6 3 5 5 2 9 3 1 2 2 2

 2 2 2 2 5 5 5 6 6 1 1 3 3 4 9
<?php
/*
  Php Program
  Sort elements by frequency
*/
class MyNumber {
	public $counter;

	function __construct() {
		$this->counter = 0;
	}
	//Combine array elements by occurrence sequence

	public 	function arrange(&$arr, $size, $index) {
		if ($index < 0) {
			return;
		}
		$data = $arr[$index];
		$this->arrange($arr, $size, $index - 1);
		for ($i = $this->counter; $i < $size && $this->counter < $size; ++$i) {
			if ($arr[$i] == $data) {
				//swap element value
				$arr[$i] = $arr[$this->counter];
				$arr[$this->counter] = $data;
				$this->counter = $this->counter + 1;
			}
		}
	}
	public 	function sort_by_frequency(&$arr, $size) {
		$sets = 1;
		$length = 0;
		for ($i = 0; $i < $size - 1; ++$i) {
			//Get the unique element

			if ($arr[$i] != $arr[$i + 1]) {
				$sets++;
			}
		}
		//Check that unique elements are more than one or not

		if ($sets > 1) {
			//Create a new memory to store frequency of element
			$record = array_fill(0, $sets,  array_fill(0, 2, 0));
			$location = 0;
			for ($i = 0; $i < $size - 1; ++$i) {
				$length++;
				if ($arr[$i] != $arr[$i + 1]) {
					//Assign value of array
					$record[$location][0] = $arr[$i];
					//Assign value of element frequency
					$record[$location][1] = $length;
					//Reset the value of new element frequency is to zero
					$length = 0;
					//modified index of record array
					$location++;
				}
			}
			if ($record[$location - 1][0] != $arr[$size - 1]) {
				//Get the frequency of last element
				$record[$location][0] = $arr[$size - 1];
				$record[$location][1] = 1;
			}
			$length = 0;
			for ($i = 0; $i < $sets; ++$i) {
				$location = $i;
				for ($j = 0; $j < $sets; ++$j) {
					if ($record[$location][1] < $record[$j][1]) {
						$location = $j;
					}
				}
				//Update actual array

				for ($k = 0; $k < $record[$location][1]; ++$k,++$length) {
					$arr[$length] = $record[$location][0];
				}
				//set frequency is -1
				$record[$location][1] = -1;
			}
			echo("\n");
		}
	}
	//print array elements

	public 	function print_array($arr, $size) {
		echo("\n");
		for ($i = 0; $i < $size; $i++) {
			echo(" ". $arr[$i]);
		}
	}
	public 	function sort_array(&$arr, $size) {
		$this->counter = 1;
		$this->print_array($arr, $size);
		$this->arrange($arr, $size, $size - 1);
		$this->sort_by_frequency($arr, $size);
		$this->print_array($arr, $size);
	}
};

function main() {
	$obj = new MyNumber();
	$arr = array(6, 5, 4, 1, 6, 3, 5, 5, 2, 9, 3, 1, 2, 2, 2);
	//Get the size of array
	$size = count($arr);
	$obj->sort_array($arr, $size);
}
main();

Output

 6 5 4 1 6 3 5 5 2 9 3 1 2 2 2

 2 2 2 2 5 5 5 6 6 1 1 3 3 4 9
Last updated on by Kalkicode




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