feat: Add solution for LeetCode problem 139

Author: WhiteHyun

word-break/WhiteHyun.swift

@@ -0,0 +1,36 @@
+//  
+//  139. Word Break
+//  https://leetcode.com/problems/word-break/description/
+//  Dale-Study
+//  
+//  Created by WhiteHyun on 2024/07/14.
+//  
+
+class Solution {
+  func wordBreak(_ s: String, _ wordDict: [String]) -> Bool {
+    var cache: [String: Bool] = [:]
+
+    func helper(_ string: String) -> Bool {
+      if let result = cache[string] {
+        return result
+      }
+
+      if string.isEmpty {
+        cache[string] = true
+        return true
+      }
+
+      for word in wordDict where string.hasPrefix(word) {
+        if helper(String(string.dropFirst(word.count))) {
+          cache[string] = true
+          return true
+        }
+      }
+
+      cache[string] = false
+      return false
+    }
+
+    return helper(s)
+  }
+}