📦 NEW: Added solution for ProjectEuler-017

omkarnathparida · omkarnathparida · commit 43e3e216542e · 2022-10-11T22:57:31.000+05:30
diff --git a/Project-Euler/Problem017.js b/Project-Euler/Problem017.js
@@ -0,0 +1,98 @@
+/**
+ * Number letter counts
+ *
+ * P.S.(Project Euler - 017):
+ * 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.
+ *
+ * If all the numbers from 1 to 1000 (one thousand) inclusive were written out in words,
+ * how many letters would be used?
+ */
+
+const ones = {
+  1: 'one',
+  2: 'two',
+  3: 'three',
+  4: 'four',
+  5: 'five',
+  6: 'six',
+  7: 'seven',
+  8: 'eight',
+  9: 'nine',
+  10: 'ten',
+  11: 'eleven',
+  12: 'twelve',
+  13: 'thirteen',
+  14: 'fourteen',
+  15: 'fifteen',
+  16: 'sixteen',
+  17: 'seventeen',
+  18: 'eighteen',
+  19: 'nineteen'
+}
+
+const tens = {
+  2: 'twenty',
+  3: 'thirty',
+  4: 'forty',
+  5: 'fifty',
+  6: 'sixty',
+  7: 'seventy',
+  8: 'eighty',
+  9: 'ninety'
+}
+
+/**
+ * Converts Number into Word
+ * @param {Number} num
+ * @returns {String} returns the converted word format of the number
+ */
+function convertNumberToLetter (num) {
+  const words = []
+
+  if (num >= 1000) {
+    words.push(ones[Math.floor(num / 1000)])
+    words.push('thousand')
+    num %= 1000
+  }
+
+  if (num >= 100) {
+    words.push(ones[Math.floor(num / 100)])
+    words.push('hundred')
+    if (num % 100 !== 0) {
+      words.push('and')
+    }
+    num %= 100
+  }
+
+  if (num >= 20) {
+    words.push(tens[Math.floor(num / 10)])
+    num %= 10
+  }
+
+  if (ones[num]) {
+    words.push(ones[num])
+  }
+
+  return words.join('')
+}
+
+/**
+ * Count total letters of converted words between two numbers
+ * @param {Number} lowNum
+ * @param {Number} highNum
+ * @returns {Number} returns the count of total letters of converted words
+ */
+export const countLetters = (lowNum, highNum) => {
+  if (lowNum > highNum) {
+    throw new Error('Minimum number can\'t be greater than Maximum number')
+  }
+  if ([lowNum, highNum].some(num => num < 1)) {
+    throw new Error('Insufficient information provided for the input')
+  }
+  const words = []
+  for (let i = lowNum; i <= highNum; i++) {
+    words.push(convertNumberToLetter(i))
+  }
+  return words.join('').length
+}
diff --git a/Project-Euler/test/Problem017.test.js b/Project-Euler/test/Problem017.test.js
@@ -0,0 +1,20 @@
+import { countLetters } from '../Problem017.js'
+
+describe('Number letter counts', () => {
+  it('should throw error when min number is greater than max number', () => {
+    expect(() => countLetters(3, 1)).toThrowError('Minimum number can\'t be greater than Maximum number')
+  })
+  it('should throw error when min number is less than 1', () => {
+    expect(() => countLetters(-5, 10)).toThrowError('Insufficient information provided for the input')
+  })
+  it('should throw error when max number is less than 1', () => {
+    expect(() => countLetters(0, 0)).toThrowError('Insufficient information provided for the input')
+  })
+  test('if the numbers are greater than 1', () => {
+    expect(countLetters(1, 5)).toBe(19)
+  })
+  // Project Euler Condition Check
+  test('if the numbers are 1 and 1000 respectively', () => {
+    expect(countLetters(1, 1000)).toBe(21124)
+  })
+})
