merge: Improved pangram algorithm using regular expressions (TheAlgorithms#906)

* feat: used regex instead of Set * docs: add js doc * docs: add comments of workable code * style: format via standardJs * docs: add details explanation of pangram regex * docs: add example * feat: add two implemetaion of The first implementation with regex and second via HashSet & add the test code for both * chore: add QNA format of **Pangram** * style: format with standardJs * resolve: removed 'Ans'

Author: fahimfaisaal

String/CheckPangram.js

@@ -1,22 +1,54 @@
-/*
-  Pangram is a sentence that contains all the letters in the alphabet
- https://en.wikipedia.org/wiki/Pangram
+/**
+ * What is Pangram?
+ * Pangram is a sentence that contains all the letters in the alphabet https://en.wikipedia.org/wiki/Pangram
  */
 
-const checkPangram = (string) => {
+/**
+ * @function checkPangramRegex
+ * @description - This function check pangram with the help of regex pattern
+ * @param {string} string
+ * @returns {boolean}
+ * @example - checkPangramRegex("'The quick brown fox jumps over the lazy dog' is a pangram") => true
+ * @example - checkPangramRegex('"Waltz, bad nymph, for quick jigs vex." is a pangram') => true
+ */
+const checkPangramRegex = (string) => {
+ if (typeof string !== 'string') {
+ throw new TypeError('The given value is not a string')
+ }
+
+ /**
+ * Match all 26 alphabets using regex, with the help of:
+ * Capturing group - () -> Groups multiple tokens together and creates a capture group for extracting a substring or using a backreference.
+ * Character set - [a-z] -> Matches a char in the range a to z in case-insensitive for the 'i' flag
+ * Negative lookahead - (?!) -> Specifies a group that can not match after the main expression (if it matches, the result is discarded).
+ * Dot - . -> Matches any character except linebreaks. Equivalent to
+ * Star - * -> Matches 0 or more of the preceding token.
+ * Numeric reference - \{$n} -> Matches the results of a capture group. E.g. - \1 matches the results of the first capture group & \3 matches the third.
+ */
+ return string.match(/([a-z])(?!.*\1)/gi).length === 26
+}
+
+/**
+ * @function checkPangramSet
+ * @description - This function detect the pangram sentence by HashSet
+ * @param {string} string
+ * @returns {boolean}
+ */
+const checkPangramSet = (string) => {
  if (typeof string !== 'string') {
  throw new TypeError('The given value is not a string')
  }
 
- const frequency = new Set()
+ const lettersSet = new Set()
 
- for (const letter of string.toLowerCase()) {
- if (letter >= 'a' && letter <= 'z') {
- frequency.add(letter)
+ for (const letter of string.toUpperCase()) {
+ if (/[A-Z]/.test(letter)) {
+ // if the letter is a valid uppercase alphabet then the add method insert the letter to the HashSet
+ lettersSet.add(letter)
  }
  }
 
- return frequency.size === 26
+ return lettersSet.size === 26
 }
 
-export { checkPangram }
+export { checkPangramRegex, checkPangramSet }

String/test/CheckPangram.test.js

@@ -1,33 +1,65 @@
-import { checkPangram } from '../CheckPangram'
+import { checkPangramRegex, checkPangramSet } from '../CheckPangram'
 
-describe('checkPangram', () => {
+describe('Testing checkPangramRegex function', () => {
  it('"The quick brown fox jumps over the lazy dog" is a pangram', () => {
  expect(
- checkPangram('The quick brown fox jumps over the lazy dog')
- ).toBeTruthy()
+ checkPangramRegex('The quick brown fox jumps over the lazy dog')
+ ).toBe(true)
  })
 
  it('"Waltz, bad nymph, for quick jigs vex." is a pangram', () => {
- expect(checkPangram('Waltz, bad nymph, for quick jigs vex.')).toBeTruthy()
+ expect(checkPangramRegex('Waltz, bad nymph, for quick jigs vex.')).toBe(true)
  })
 
  it('"Jived fox nymph grabs quick waltz." is a pangram', () => {
- expect(checkPangram('Jived fox nymph grabs quick waltz.')).toBeTruthy()
+ expect(checkPangramRegex('Jived fox nymph grabs quick waltz.')).toBe(true)
  })
 
  it('"My name is Unknown" is NOT a pangram', () => {
- expect(checkPangram('My name is Unknown')).toBeFalsy()
+ expect(checkPangramRegex('My name is Unknown')).toBe(false)
  })
 
  it('"The quick brown fox jumps over the la_y dog" is NOT a pangram', () => {
  expect(
- checkPangram('The quick brown fox jumps over the la_y dog')
- ).toBeFalsy()
+ checkPangramRegex('The quick brown fox jumps over the la_y dog')
+ ).toBe(false)
  })
 
  it('Throws an error if given param is not a string', () => {
  expect(() => {
- checkPangram(undefined)
+ checkPangramRegex(undefined)
+ }).toThrow('The given value is not a string')
+ })
+})
+
+describe('Testing checkPangramSet function', () => {
+ it('"The quick brown fox jumps over the lazy dog" is a pangram', () => {
+ expect(
+ checkPangramSet('The quick brown fox jumps over the lazy dog')
+ ).toBe(true)
+ })
+
+ it('"Waltz, bad nymph, for quick jigs vex." is a pangram', () => {
+ expect(checkPangramSet('Waltz, bad nymph, for quick jigs vex.')).toBe(true)
+ })
+
+ it('"Jived fox nymph grabs quick waltz." is a pangram', () => {
+ expect(checkPangramSet('Jived fox nymph grabs quick waltz.')).toBe(true)
+ })
+
+ it('"My name is Unknown" is NOT a pangram', () => {
+ expect(checkPangramSet('My name is Unknown')).toBe(false)
+ })
+
+ it('"The quick brown fox jumps over the la_y dog" is NOT a pangram', () => {
+ expect(
+ checkPangramSet('The quick brown fox jumps over the la_y dog')
+ ).toBe(false)
+ })
+
+ it('Throws an error if given param is not a string', () => {
+ expect(() => {
+ checkPangramSet(undefined)
  }).toThrow('The given value is not a string')
  })
 })