剑指 Offer II 032. 有效的变位词

注意“a” 和 “a” 不是变位词= =。。

func isAnagram(_ s: String, _ t: String) -> Bool {
     
      let m = s.count
      let n = t.count
      if m != n || m == 1 && n == 1 {
          return false
      }
     
      
      
      var dict = Dictionary<Character,Int>()
      for c in s {
          if let count = dict[c] {
              dict[c] = count + 1
          }
          else{
              dict[c] = 1
          }
      }
      
      for c1 in t {
          if let count = dict[c1]{
              dict[c1] = count - 1
              if count - 1 == 0 {
                  dict.removeValue(forKey: c1)
              }
          }
          
      }
      
      if dict.keys.count == 0 {
          return true
      }else {
          return false
      }
  
  }