generated from mwc/problemset_numberwords
94 lines
3.2 KiB
Markdown
94 lines
3.2 KiB
Markdown
# Planning Number Words
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Before you start programming, do some planning here on how you will break down
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this problem. Here's a hint: if you start by writing functions for smaller numbers,
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you will find that these functions help you with the larger numbers. For each of
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the cases below, explain how you would turn a number into a string. Feel free to
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write in sentences or in pseudocode (pseudocode is a sort of "casual programming"
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where you're almost writing in code, being pretty specific without worrying about
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syntax. For each case below, assume the integer is zero or more--don't worry about
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negative integers.
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## Integers under 10
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(This one is done for you!)
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For an integer less than ten, you need to know the name of each digit, and look it
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up. You could use a big if/else statement like:
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```
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if number == 0:
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return "zero"
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elif number == 1:
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return "one"
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elif number == 1:
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return "two"
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```
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A cleaner way to do this would be to make a list of digit names, from zero to nine.
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Then you could just look up a digit's name:
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```
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digit_names = [
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"zero", "one", "two", "three", "four",
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"five", "six", "seven", "eight", "nine"
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]
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return digit_names[number]
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```
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## Integers under 20
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If the integer is under 10, then use the procedure described above.
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Otherwise, ... (this is where you take over!)
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We can again make a list of digit names:
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```
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digit_names = [
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"zero", "one", "two", "three", "four",
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"five", "six", "seven", "eight", "nine",
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"ten", "eleven", "twelve", "thirteen",
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"fourteen", "fifteen", "sixteen",
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"seventeen", "eighteen", "nineteen"
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]
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return digit_names[number]
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```
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## Integers under 100
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If the integer is under 20, then use the procedure described above.
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Otherwise,
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First, create a list of tens digit strings:
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```
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tens_names = [
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"twenty", "thirty", "forty", "fifty",
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"sixty", "seventy", "eighty", "ninety"
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]
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```
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Second, determine the leading digit, using integer division by 10, and the ones digit using mod 10 and look up the correct names.
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return tens_names[number / 10 - 2] + digit_names[number % 10]
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## Integers under 1000
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If the integer is under 100, then use the procedure described above. We'll call that procedure tens_number().
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Otherwise,
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First, create a list of hundreds digit srings:
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```
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hundreds_names = [
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"one hundred", "two hundred", "three hundred",
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"four hundred", "five hundred", "six hundred",
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"seven hundred", "eight hundred", "nine hundred"
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]
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```
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Second determine the hundreds digit using integer division by one hundred, the tens digit by finding the number mod 100 and applying tens_number(), and the ones digit by finding the number mod 10.
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return hundreds_name[number / 100] + tens_number(number % 100) + digit_names[number % 10]
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## Integers under 1000000
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If the integer is under 1000, then use the procedure described above. We'll call that procedure hundreds_name().
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return hundreds_name(number / 1000) + "thousand" + hundreds_name(number % 1000)
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## Negative integers down to -1 million
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We won't deal with negative integers in this problem set,
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but how would you deal with a negative integer, using the
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functions above?
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If the number is positive, use the above method.
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Otherwise, return "negative " + number_words(-1 * number) |