0001.两数之和：简化Swift实现

problems/0001.两数之和.md

@@ -207,18 +207,16 @@ function twoSum(array $nums, int $target): array
 Swift：
 ```swift
 func twoSum(_ nums: [Int], _ target: Int) -> [Int] {
-    var res = [Int]()
-    var dict = [Int : Int]()
-    for i in 0 ..< nums.count {
-        let other = target - nums[i]
-        if dict.keys.contains(other) {
-            res.append(i)
-            res.append(dict[other]!)
-            return res
+    // 值: 下标
+    var map = [Int: Int]()
+    for (i, e) in nums.enumerated() {
+        if let v = map[target - e] {
+            return [v, i]
+        } else {
+            map[e] = i
         }
-        dict[nums[i]] = i
     }
-    return res
+    return []
 }
 ```