feat: add swift implementation to lcof problem: No.63 (doocs#2958)

Author: klever34

lcof/面试题63. 股票的最大利润/README.md

@@ -174,6 +174,24 @@ public class Solution {
 }
 ```
 
+#### Swift
+
+```swift
+class Solution {
+    func maxProfit(_ prices: [Int]) -> Int {
+        var mi = Int.max
+        var ans = 0
+        
+        for x in prices {
+            ans = max(ans, x - mi)
+            mi = min(mi, x)
+        }
+        
+        return ans
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

lcof/面试题63. 股票的最大利润/Solution.swift

@@ -0,0 +1,13 @@
+class Solution {
+    func maxProfit(_ prices: [Int]) -> Int {
+        var mi = Int.max
+        var ans = 0
+        
+        for x in prices {
+            ans = max(ans, x - mi)
+            mi = min(mi, x)
+        }
+        
+        return ans
+    }
+}