添加 383. 赎金信 Swift版本

problems/0383.赎金信.md

@@ -266,6 +266,28 @@ var canConstruct = function(ransomNote, magazine) {
 };
 ```
 
+Swift：
+```swift
+func canConstruct(_ ransomNote: String, _ magazine: String) -> Bool {
+    var record = Array(repeating: 0, count: 26);
+    let aUnicodeScalarValue = "a".unicodeScalars.first!.value
+    for unicodeScalar in magazine.unicodeScalars {
+        // 通过record 记录 magazine 里各个字符出现的次数
+        let idx: Int = Int(unicodeScalar.value - aUnicodeScalarValue)
+        record[idx] += 1
+    }
+    for unicodeScalar in ransomNote.unicodeScalars {
+        // 遍历 ransomNote,在record里对应的字符个数做 -- 操作
+        let idx: Int = Int(unicodeScalar.value - aUnicodeScalarValue)
+        record[idx] -= 1
+        // 如果小于零说明在magazine没有
+        if record[idx] < 0 {
+            return false
+        }
+    }
+    return true
+}
+```
 
 
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