Code Challenge

Self Describing Number

Task Description

• Write a function named isSelfDescribing that will check whether a given positive integer is self-describing (returns true) or not (returns false)

There are several so-called "self-describing" or "self-descriptive" integers.

An integer is said to be "self-describing" if it has the property that, when digit positions are labeled 0 to N-1, the digit in each position is equal to the number of times that that digit appears in the number.

For example,   2020   is a four-digit self describing number:

•   Position   0   has value   2   and there are two 0s in the number
•   Position   1   has value   0   and there are no 1s in the number
•   Position   2   has value   2   and there are two 2s
•   Position   3   has value   0   and there are zero 3s

Self-describing numbers < 100.000.000  are: 1210, 2020, 21200, 3211000, 42101000.

 

Source: Self-describing numbers - Rosetta Code

[2, 0, 2, 0]