feat: add swift solution 2 implementation to lcof2 problem: No.098 (doocs#3504)

Author: klever34

lcof2/剑指 Offer II 098. 路径的数目/README.md

@@ -386,6 +386,24 @@ var uniquePaths = function (m, n) {
 };
 ```
 
+#### Swift
+
+```swift
+class Solution {
+    func uniquePaths(_ m: Int, _ n: Int) -> Int {
+        var dp = Array(repeating: Array(repeating: 1, count: n), count: m)
+
+        for i in 1..<m {
+            for j in 1..<n {
+                dp[i][j] = dp[i-1][j] + dp[i][j-1]
+            }
+        }
+
+        return dp[m-1][n-1]
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

lcof2/剑指 Offer II 098. 路径的数目/Solution2.swift

@@ -0,0 +1,13 @@
+class Solution {
+    func uniquePaths(_ m: Int, _ n: Int) -> Int {
+        var dp = Array(repeating: Array(repeating: 1, count: n), count: m)
+
+        for i in 1..<m {
+            for j in 1..<n {
+                dp[i][j] = dp[i-1][j] + dp[i][j-1]
+            }
+        }
+
+        return dp[m-1][n-1]
+    }
+}