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// An [Anagram](https://en.wikipedia.org/wiki/Anagram) is a string that is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once.
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// Anagram check is case sensitive; i.e. Aba and aba is not a anagram.
// inputs are strings i.e. str1 and str2
const checkAnagram = ( str1 , str2 ) => {
// check that inputs are strings.
if ( typeof str1 !== 'string' || typeof str2 !== 'string' ) {
return 'Not string(s)'
}
// If both strings have not same lengths then they can not be anagram.
if ( str1 . length !== str2 . length ) {
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return false
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}
// Use hashmap to keep count of characters in str1
const str1CharCount = new Map ( )
for ( let i = 0 ; i < str1 . length ; i ++ ) {
let previousCount = 0
if ( str1CharCount . has ( str1 [ i ] ) ) {
previousCount = str1CharCount . get ( str1 [ i ] )
}
str1CharCount . set ( str1 [ i ] , previousCount + 1 )
}
// Now check if second string has same characters?
for ( let i = 0 ; i < str2 . length ; i ++ ) {
let previousCount = 0
// if str1CharCount has no key for str2[i] then not anagram.
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if ( ! str1CharCount . has ( str2 [ i ] ) ) return false
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previousCount = str1CharCount . get ( str2 [ i ] )
str1CharCount . set ( str2 [ i ] , previousCount - 1 )
}
// Now check if all entries in hashmap has zeros.
for ( const key in str1CharCount ) {
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if ( str1CharCount [ key ] !== 0 ) return false
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}
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return true
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}
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export { checkAnagram }
