digit-count – Count of decimal digits – Computer Science by Example

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digit-count – Count of decimal digits

Write a program counts how many times given digits appear in given integers. For example:

the digit 7 appears one time in the number 720;
the digit 3 appears two times in the number 1337.

Counts of digits in 720 and 1337

Input and Output

Input will consist of several lines each with a digit d and a number x where:

0 ≤ d ≤ 9

0 ≤ x ≤ 1 000 000 000

For each line of input, output should contain a single line with a number c indicating the number of times the digit d appears on x. Leading zeroes should be ignored, they should not account towards the count.

Input is terminated by the end-of-file (EOF).

Example Input

Example Output

The “digit count” function

Your program should be implemented using a “digit count” function that receives two integers, the digit d and the number x, and returns an integer indicating how many times the digit d appears in the number x. Please refer to the information for the chosen language:

Python definition: def digit_count(d, x):
C prototype: int digit_count(int d, int x);
Haskell type: digitCount :: Int -> Int -> Int
C++ prototype: int digit_count(int d, int x);
C# definition: public static int DigitCount(int d, int i) in a public class Program
Java definition: public static int digitCount(int d, int i) in a public class DigitCount
JavaScript definition: function digit_count(d,i)
Lua definition: function digit_count (d, x)
Ruby definition: def digit_count(d,i)

Scoring

Submit your solution to be graded according to the following list:

1/6: works for the above example but produces output in an incorrect format
2/6: works for the above example and produces output in the correct format
4/6: works for other test cases
5/6: works for edge cases
6/6: implements the “digit count” function

Hints

Here are some hints:

Automated judge: Keep in mind that when your program is submitted it will not be run by a human but instead by an automated judge. Instructions should be followed exactly or the judge will not give you a full score. (And sometimes no score at all!)
Produce output as you go: You do not need to accumulate input and then produce everything at the end. It is enough to produce output as you go. As soon as you read a pair of numbers, write the corresponding result to the screen.
Detecting the end of file. In this exercise, input is terminated by the end-of-file (EOF). The EOF can be simulated by the “ctrl-D” keystroke on the terminal/console session. Please see “processing input line by line” for details on how to do this.
Processing digits. You can isolate the last digit of an integer by computing the remainder of the division by 10 (a.k.a. modulo). Likewise, you can remove the last digit by dividing a number by 10.

try first: digit-sum add mult

try next: digit-reverse

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