merge: Upgrade max char (TheAlgorithms#983)

* feat: improved memoize function used Map instead of object & used the JSON.stringfy method for generate a valid string as a key * docs: modified documentation * style: format with standard * docs: modified stringify doc * refactor: remove two repetition implementation * feat: added validation, test codes * chore: remove useless words * feat: added types for jest * chore: added link box * feat: added new validation test casses & methods * style: formated with standard * feat: added parse method & test cases * docs: added js docs * chore: added default import export * feat: imporved algorithm via replace method * test: added two test cases * feat: added jest type for suggestions * feat: added `reduceRight` & `trim` method * chore: added helper variable * feat: added new rotation option * Revert "chore: added helper variable" This reverts commit 489544d. * remove: yarn lock * chore: fix grammer * feat: used replace method & added test case * feat: remove revert * chore: added new line * feat: added filter for alphabets only * resolve: added empty validation improved ignore pattern * chore: reverted to for of loop

Author: fahimfaisaal

String/MaxCharacter.js

@@ -1,29 +1,36 @@
-/*
- Given a string of characters, return the character that appears the most often.
- Example: input = "Hello World!" return "l"
-*/
-const maxCharacter = (value) => {
- if (typeof value !== 'string') {
- throw new TypeError('The param should be a string')
- } else if (!value) {
- throw new Error('The param should be a valid string')
+/**
+ * @function maxCharacter
+ * @example - Given a string of characters, return the character that appears the most often. Example: input = "Hello World!" return "l"
+ * @param {string} str
+ * @param {RegExp} ignorePattern - ignore the char in str that is not required
+ * @returns {string} - char
+ */
+const maxCharacter = (str, ignorePattern) => { // initially it's count only alphabets
+ if (typeof str !== 'string') {
+ throw new TypeError('Argument should be a string')
+ } else if (!str) {
+ throw new Error('The param should be a nonempty string')
  }
 
- const occurrences = {}
- for (let i = 0; i < value.length; i++) {
- const char = value[i]
- if (/\s/.test(char)) continue
- occurrences[char] = occurrences[char] + 1 || 1
+ // store all char in occurrence map
+ const occurrenceMap = new Map()
+
+ for (const char of str) {
+ if (!ignorePattern?.test(char)) {
+ occurrenceMap.set(char, occurrenceMap.get(char) + 1 || 1)
+ }
  }
- let maxCharacter = null
- let maxCount = 0
- Object.keys(occurrences).forEach(char => {
- if (occurrences[char] > maxCount) {
- maxCount = occurrences[char]
- maxCharacter = char
+
+ // find the max char from the occurrence map
+ let max = { char: '', occur: -Infinity }
+
+ for (const [char, occur] of occurrenceMap) {
+ if (occur > max.occur) {
+ max = { char, occur }
  }
- })
- return maxCharacter
+ }
+
+ return max.char
 }
 
-export { maxCharacter }
+export default maxCharacter

String/test/MaxCharacter.test.js

@@ -1,12 +1,21 @@
-import { maxCharacter } from '../MaxCharacter'
+import maxCharacter from '../MaxCharacter'
 
 describe('Testing the maxCharacter function', () => {
  it('Expect throw with wrong arg', () => {
  expect(() => maxCharacter(123)).toThrow()
+ expect(() => maxCharacter('')).toThrow()
  })
+
  it('Check the max character in string', () => {
  const theString = 'I can\'t do that'
- const maxChar = maxCharacter(theString)
+ const maxCharInAllCount = maxCharacter(theString)
+ const maxChar = maxCharacter(theString, /\s/)
+
+ expect(maxCharInAllCount).toBe(' ')
  expect(maxChar).toBe('t')
+
+ expect(maxCharacter('!!!Hello, World!!!', /[a-z]/)).toBe('!')
+
+ expect(maxCharacter('!!!Hello, World!!!', /[^a-z]/i)).toBe('l')
  })
 })