feat: add swift implementation to lcci problem: No.16.18 (#2761)

Author: klever34

lcci/16.18.Pattern Matching/README.md

@@ -292,6 +292,72 @@ function patternMatching(pattern: string, value: string): boolean {
 }
 ```
 
+```swift
+class Solution {
+    private var pattern: String = ""
+    private var value: String = ""
+
+    func patternMatching(_ pattern: String, _ value: String) -> Bool {
+        self.pattern = pattern
+        self.value = value
+        var cnt = [Int](repeating: 0, count: 2)
+        for c in pattern {
+            cnt[Int(c.asciiValue! - Character("a").asciiValue!)] += 1
+        }
+        let n = value.count
+        if cnt[0] == 0 {
+            return n % cnt[1] == 0 && String(repeating: String(value.prefix(n / cnt[1])), count: cnt[1]) == value
+        }
+        if cnt[1] == 0 {
+            return n % cnt[0] == 0 && String(repeating: String(value.prefix(n / cnt[0])), count: cnt[0]) == value
+        }
+        for la in 0...n {
+            if la * cnt[0] > n {
+                break
+            }
+            if (n - la * cnt[0]) % cnt[1] == 0 {
+                let lb = (n - la * cnt[0]) / cnt[1]
+                if check(la, lb) {
+                    return true
+                }
+            }
+        }
+        return false
+    }
+
+    private func check(_ la: Int, _ lb: Int) -> Bool {
+        var a: String? = nil
+        var b: String? = nil
+        var index = value.startIndex
+
+        for c in pattern {
+            if c == "a" {
+                let end = value.index(index, offsetBy: la)
+                if let knownA = a {
+                    if knownA != value[index..<end] {
+                        return false
+                    }
+                } else {
+                    a = String(value[index..<end])
+                }
+                index = end
+            } else {
+                let end = value.index(index, offsetBy: lb)
+                if let knownB = b {
+                    if knownB != value[index..<end] {
+                        return false
+                    }
+                } else {
+                    b = String(value[index..<end])
+                }
+                index = end
+            }
+        }
+        return a != b
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- end -->

lcci/16.18.Pattern Matching/README_EN.md

@@ -307,6 +307,72 @@ function patternMatching(pattern: string, value: string): boolean {
 }
 ```
 
+```swift
+class Solution {
+    private var pattern: String = ""
+    private var value: String = ""
+
+    func patternMatching(_ pattern: String, _ value: String) -> Bool {
+        self.pattern = pattern
+        self.value = value
+        var cnt = [Int](repeating: 0, count: 2)
+        for c in pattern {
+            cnt[Int(c.asciiValue! - Character("a").asciiValue!)] += 1
+        }
+        let n = value.count
+        if cnt[0] == 0 {
+            return n % cnt[1] == 0 && String(repeating: String(value.prefix(n / cnt[1])), count: cnt[1]) == value
+        }
+        if cnt[1] == 0 {
+            return n % cnt[0] == 0 && String(repeating: String(value.prefix(n / cnt[0])), count: cnt[0]) == value
+        }
+        for la in 0...n {
+            if la * cnt[0] > n {
+                break
+            }
+            if (n - la * cnt[0]) % cnt[1] == 0 {
+                let lb = (n - la * cnt[0]) / cnt[1]
+                if check(la, lb) {
+                    return true
+                }
+            }
+        }
+        return false
+    }
+
+    private func check(_ la: Int, _ lb: Int) -> Bool {
+        var a: String? = nil
+        var b: String? = nil
+        var index = value.startIndex
+
+        for c in pattern {
+            if c == "a" {
+                let end = value.index(index, offsetBy: la)
+                if let knownA = a {
+                    if knownA != value[index..<end] {
+                        return false
+                    }
+                } else {
+                    a = String(value[index..<end])
+                }
+                index = end
+            } else {
+                let end = value.index(index, offsetBy: lb)
+                if let knownB = b {
+                    if knownB != value[index..<end] {
+                        return false
+                    }
+                } else {
+                    b = String(value[index..<end])
+                }
+                index = end
+            }
+        }
+        return a != b
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- end -->

lcci/16.18.Pattern Matching/Solution.swift

@@ -0,0 +1,63 @@
+class Solution {
+    private var pattern: String = ""
+    private var value: String = ""
+
+    func patternMatching(_ pattern: String, _ value: String) -> Bool {
+        self.pattern = pattern
+        self.value = value
+        var cnt = [Int](repeating: 0, count: 2)
+        for c in pattern {
+            cnt[Int(c.asciiValue! - Character("a").asciiValue!)] += 1
+        }
+        let n = value.count
+        if cnt[0] == 0 {
+            return n % cnt[1] == 0 && String(repeating: String(value.prefix(n / cnt[1])), count: cnt[1]) == value
+        }
+        if cnt[1] == 0 {
+            return n % cnt[0] == 0 && String(repeating: String(value.prefix(n / cnt[0])), count: cnt[0]) == value
+        }
+        for la in 0...n {
+            if la * cnt[0] > n {
+                break
+            }
+            if (n - la * cnt[0]) % cnt[1] == 0 {
+                let lb = (n - la * cnt[0]) / cnt[1]
+                if check(la, lb) {
+                    return true
+                }
+            }
+        }
+        return false
+    }
+
+    private func check(_ la: Int, _ lb: Int) -> Bool {
+        var a: String? = nil
+        var b: String? = nil
+        var index = value.startIndex
+
+        for c in pattern {
+            if c == "a" {
+                let end = value.index(index, offsetBy: la)
+                if let knownA = a {
+                    if knownA != value[index..<end] {
+                        return false
+                    }
+                } else {
+                    a = String(value[index..<end])
+                }
+                index = end
+            } else {
+                let end = value.index(index, offsetBy: lb)
+                if let knownB = b {
+                    if knownB != value[index..<end] {
+                        return false
+                    }
+                } else {
+                    b = String(value[index..<end])
+                }
+                index = end
+            }
+        }
+        return a != b
+    }
+}