[Swift]LeetCode242. 有效的字母异位词 | Valid Anagram

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➤微信公众号：山青咏芝（shanqingyongzhi）
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Given two strings s and t , write a function to determine if t is an anagram of s.

Example 1:

Input: s = "anagram", t = "nagaram"
Output: true

Example 2:

Input: s = "rat", t = "car"
Output: false

Note:
You may assume the string contains only lowercase alphabets.

Follow up:
What if the inputs contain unicode characters? How would you adapt your solution to such case?

给定两个字符串 s 和 t ，编写一个函数来判断 t 是否是 s 的一个字母异位词。

示例 1:

输入: s = "anagram", t = "nagaram"
输出: true

示例 2:

输入: s = "rat", t = "car"
输出: false

说明:
你可以假设字符串只包含小写字母。

进阶:
如果输入字符串包含 unicode 字符怎么办？你能否调整你的解法来应对这种情况？

---

32ms

class Solution {
    func isAnagram(_ s: String, _ t: String) -> Bool {
        
      let chars_S = s.unicodeScalars
      var counter_S = Array(repeating: 0, count: 26)
      let chars_T = t.unicodeScalars
      var counter_T = Array(repeating: 0, count: 26)

      for char in chars_S {
        let index = Int(char.value - 97)
        counter_S[index] += 1
      }

      for char in chars_T {
        let index = Int(char.value - 97)
        counter_T[index] += 1
      }
      return counter_T == counter_S
    }
}

---

32ms

class Solution {
    func isAnagram(_ s: String, _ t: String) -> Bool {
        guard s.count == t.count else {
            return false
        }
        var occurances = [Int](repeating: 0, count: 26)
        let aValue: UInt8 = 97
        for char in s.utf8 {
            occurances[Int(char - aValue)] += 1
        }
        for char in t.utf8 {
            occurances[Int(char - aValue)] -= 1
        }
        for value in occurances {
            if value != 0 {
                return false
            }
        }
        return true
    }
}

---

48ms

class Solution {
    func isAnagram(_ s: String, _ t: String) -> Bool {
        return t.unicodeScalars.reduce(into: [:]) { $0[$1, default: 0] += 1 } == s.unicodeScalars.reduce(into: [:]) { $0[$1, default: 0] += 1 }
    }
}

---

64ms

extension Character {
    
    var ascii: Int {
        return Int(unicodeScalars.first!.value)
    }
    
}

class Solution {
    func isAnagram(_ s: String, _ t: String) -> Bool {
        var table = [Int](repeating: 0, count: 128)

        for char in s {
            table[char.ascii] += 1
        }

        for char in t {
            table[char.ascii] -= 1
        }

        for ascii in 97...122 {
            if table[ascii] != 0 {
                return false
            }
        }

        return true
    }
}

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