Is Anagram

Write a function that determines if one string is an anagram of another string.

An anagram is rearranging letters of words or phrases to create new words or phrases. For example, “debit card” and “bad credit” are anagrams of each other.

func isAnagram(s1: String, s2: String) -> Bool {
  var counts = [Character: Int]()
  
  for c in s1 {
    let count = counts[c] ?? 0
    counts[c] = count + 1
  }
  
  for c in s2 {
    let count = counts[c] ?? 0
    
    if count <= 0 {
      return false
    }
    
    counts[c] = count - 1
  }
  
  for (_, count) in counts {
    if count != 0 {
      return false
    }
  }
  
  return true
}

isAnagram(s1:"elvis", s2:"lives")
isAnagram(s1:"eleven plus two", s2:"twelve plus one")
isAnagram(s1:"debit card", s2:"bad credit")
isAnagram(s1:"abc", s2:"123")
isAnagram(s1:"cinema", s2:"iceman")