feat: add swift implementation to lcof2 problem: No.097 (#3484)

Author: klever34

lcof2/剑指 Offer II 097. 子序列的数目/README.md

@@ -202,6 +202,36 @@ function numDistinct(s: string, t: string): number {
 }
 ```
 
+#### Swift
+
+```swift
+class Solution {
+    func numDistinct(_ s: String, _ t: String) -> Int {
+        let m = s.count, n = t.count
+        let sArray = Array(s)
+        let tArray = Array(t)
+
+        var dp = Array(repeating: Array(repeating: 0, count: n + 1), count: m + 1)
+
+
+        for i in 0...m {
+            dp[i][0] = 1
+        }
+
+        for i in 1...m {
+            for j in 1...n {
+                dp[i][j] = dp[i - 1][j]
+                if sArray[i - 1] == tArray[j - 1] {
+                    dp[i][j] += dp[i - 1][j - 1]
+                }
+            }
+        }
+
+        return dp[m][n]
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

lcof2/剑指 Offer II 097. 子序列的数目/Solution.swift

@@ -0,0 +1,25 @@
+class Solution {
+    func numDistinct(_ s: String, _ t: String) -> Int {
+        let m = s.count, n = t.count
+        let sArray = Array(s)
+        let tArray = Array(t)
+        
+        var dp = Array(repeating: Array(repeating: 0, count: n + 1), count: m + 1)
+        
+        
+        for i in 0...m {
+            dp[i][0] = 1
+        }
+        
+        for i in 1...m {
+            for j in 1...n {
+                dp[i][j] = dp[i - 1][j]
+                if sArray[i - 1] == tArray[j - 1] {
+                    dp[i][j] += dp[i - 1][j - 1]
+                }
+            }
+        }
+        
+        return dp[m][n]
+    }
+}