Frequencies of Limited Range Array Elements Python

PROGRAM TO COUNT FREQUENCIES OF ALL ELEMENTS OF ALL ELEMENTS IN ARRAY 




# Function to find counts of all elements

# present in arr[0..n-1]. The array

# elements must be range from 1 to n

def printfrequency(arr, n):

 

    # Subtract 1 from every element so that

    # the elements become in range from 0 to n-1

    for j in range(n):

        arr[j] = arr[j] - 1

 

    # Use every element arr[i] as index

    # and add 'n' to element present at

    # arr[i]%n to keep track of count of

    # occurrences of arr[i]

    for i in range(n):

        arr[arr[i] % n] = arr[arr[i] % n] + n

 

    # To print counts, simply print the

    # number of times n was added at index

    # corresponding to every element

    for i in range(n):

        print(i + 1, "->", arr[i] // n)

 

# Driver code

arr = [2, 3, 3, 2, 5]

n = len(arr)

printfrequency(arr, n)







OUTPUT

1 ->  0
2 ->  2
3 ->  2
4 ->  0
5 ->  1

CREDITS: https://www.geeksforgeeks.org/count-frequencies-elements-array-o1-extra-space-time/