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86d333ee94
* chore: Switch to Node 20 + Vitest * chore: migrate to vitest mock functions * chore: code style (switch to prettier) * test: re-enable long-running test Seems the switch to Node 20 and Vitest has vastly improved the code's and / or the test's runtime! see #1193 * chore: code style * chore: fix failing tests * Updated Documentation in README.md * Update contribution guidelines to state usage of Prettier * fix: set prettier printWidth back to 80 * chore: apply updated code style automatically * fix: set prettier line endings to lf again * chore: apply updated code style automatically --------- Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com> Co-authored-by: Lars Müller <34514239+appgurueu@users.noreply.github.com>
118 lines
3.2 KiB
JavaScript
118 lines
3.2 KiB
JavaScript
/**
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* Problem 17 - Number letter counts
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*
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* @see {@link https://projecteuler.net/problem=17}
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*
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* If the numbers 1 to 5 are written out in words: one, two, three, four, five, then there are 3 + 3 + 5 + 4 + 4 = 19 letters used in total.
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* If all the numbers from 1 to 1000 (one thousand) inclusive were written out in words, how many letters would be used?
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*
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* @author Chetan07j
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*/
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// Array of number word length from 0 -> 19
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const ones = [4, 3, 3, 5, 4, 4, 3, 5, 5, 4, 3, 6, 6, 8, 8, 7, 7, 9, 8, 8]
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// Array for tens from 20, 30, 40, 50, 60, 70, 80, 90 in words length
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const tens = [6, 6, 5, 5, 5, 7, 6, 6]
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// Word length for words thousand, hundred, and
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const thousandLength = 8
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const hundredLength = 7
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const andLength = 3
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/**
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* Function to convert number to word
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*
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* This function is called recursively to handle thousand and its sub part
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*/
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const numberToWordLength = (n) => {
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let count = 0
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// If number is < 20 then return its corresponding value from ones
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if (n < 20) {
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return ones[n]
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}
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/**
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* To calculate tens value "n / 10 - 2" is performed, which might return decimal value
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* to extract proper integer value Math.floor is added
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* Here "-2" is performed as our tens array start with index 0
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* To get appropriate value from that for our number it is required
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* e.g.,
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* -> 34 -> 34/10= 3.4 -> Math.floor(3.4) = 3
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* -> ones[3] = 5 // this is wrong
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* -> 3 - 2 = 1 -> ones[1] = 6
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*
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* To find ones part, unit is identified by n % 10
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* If > 0 then ones word is appended to tens word otherwise nothing
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* e.g.,
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* 1. 34 -> 10
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* 2. 30 -> 6
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*/
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if (n >= 20 && n < 100) {
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const unit = n % 10
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return tens[Math.floor(n / 10 - 2)] + (unit !== 0 ? ones[unit] : 0)
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}
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// Find thousand, hundred and sub part
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const hundred = Math.floor(n / 100) % 10
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const thousand = Math.floor(n / 1000)
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const sub = n % 100
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// Find ones for thousand part number
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// e.g., thousand = 2 => inWord = twothousand
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if (n > 999) {
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count += numberToWordLength(thousand) + thousandLength
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}
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// Find ones for hundred part number
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// e.g., hundred = 1 => inWord = onehundred
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if (hundred !== 0) {
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count += ones[hundred] + hundredLength
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}
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// Find and part of number
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// e.g., 922 => ninehundred"andtwentytwo"
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if (sub !== 0) {
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count += andLength + numberToWordLength(sub)
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}
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// return number in word format
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return count
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}
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/**
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* Function responsible for calculating total number word length
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* for provided input number
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* Validation is performed for input
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* Loop is executed to find total word length for given number range
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* starting from 1
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*
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*
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* @param {number} number
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* @returns {number}
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*/
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const countNumberWordLength = (number) => {
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let count = 0
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// Not a number check
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if (Number.isNaN(parseInt(number))) {
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throw new Error('Invalid input, please provide valid number')
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}
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// Number should be greater than 1
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if (number < 1) {
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throw new Error('Please provide number greater that 1')
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}
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// Loop to calculate word length by calling {@link numberToWord}
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for (let i = 1; i <= number; i++) {
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count += numberToWordLength(i)
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}
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// return final count for number word length
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return count
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}
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export { countNumberWordLength }
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