From 44c8ea7244cc297b24f8708fccff2b9a0ef59be7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=EB=91=90=EB=A6=AC?= <kdle_@naver.com>
Date: Sat, 3 May 2025 15:22:01 +0900
Subject: [PATCH 1/4] Solution Best Time to Buy and Sell Stock

---
 best-time-to-buy-and-sell-stock/doitduri.swift | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 best-time-to-buy-and-sell-stock/doitduri.swift

diff --git a/best-time-to-buy-and-sell-stock/doitduri.swift b/best-time-to-buy-and-sell-stock/doitduri.swift
new file mode 100644
index 000000000..69d5c2b7b
--- /dev/null
+++ b/best-time-to-buy-and-sell-stock/doitduri.swift
@@ -0,0 +1,18 @@
+class Solution {
+    func maxProfit(_ prices: [Int]) -> Int {
+        guard var anchor = prices.first, prices.count > 1 else {
+            return 0
+        }
+        
+        var result = 0
+        for price in prices {
+            if price < anchor {
+                anchor = price
+            } else if price - anchor > result {
+                result = price - anchor
+            }
+        }
+        
+        return result
+    }
+}

From 425262dad77fd6eee8f4ce08b1d703357a04ed0b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=EB=91=90=EB=A6=AC?= <kdle_@naver.com>
Date: Sat, 3 May 2025 15:45:22 +0900
Subject: [PATCH 2/4] Solution Group Anagrams

---
 group-anagrams/doitduri.swift | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
 create mode 100644 group-anagrams/doitduri.swift

diff --git a/group-anagrams/doitduri.swift b/group-anagrams/doitduri.swift
new file mode 100644
index 000000000..36dd78e3b
--- /dev/null
+++ b/group-anagrams/doitduri.swift
@@ -0,0 +1,16 @@
+class Solution {
+    func groupAnagrams(_ strs: [String]) -> [[String]] {
+        var groups: [String: [String]] = [:]
+        
+        for str in strs {
+            let sortedStr = String(str.sorted())
+            
+            var values = groups[sortedStr] ?? []
+            values.append(str)
+            
+            groups[sortedStr] = values
+        }
+        
+        return Array(groups.values)
+    }
+}

From 87883304fae3a81be02c6f246d10e21712a9b305 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=EB=91=90=EB=A6=AC?= <kdle_@naver.com>
Date: Sat, 3 May 2025 16:28:40 +0900
Subject: [PATCH 3/4] Solution Word break

---
 word-break/doitduri.swift | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)
 create mode 100644 word-break/doitduri.swift

diff --git a/word-break/doitduri.swift b/word-break/doitduri.swift
new file mode 100644
index 000000000..57d9097d9
--- /dev/null
+++ b/word-break/doitduri.swift
@@ -0,0 +1,26 @@
+class Solution {
+    func wordBreak(_ s: String, _ wordDict: [String]) -> Bool {
+        let wordSet = Set(wordDict)
+        var dp = Array(repeating: false, count: s.count + 1)
+        
+        dp[0] = true
+        
+        for i in 1...s.count {
+            for j in 0..<i {
+                
+                guard dp[j] else { continue }
+                
+                let startIndex = s.index(s.startIndex, offsetBy: j)
+                let endIndex = s.index(s.startIndex, offsetBy: i)
+                let word = String(s[startIndex..<endIndex])
+                
+                if wordSet.contains(word) {
+                    dp[i] = true
+                    break
+                }
+            }
+        }
+        
+        return dp[s.count]
+    }
+}

From d17c24c71230b47048a3be3223e9ee2dd69c93c0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=EB=91=90=EB=A6=AC?= <kdle_@naver.com>
Date: Sat, 3 May 2025 17:19:50 +0900
Subject: [PATCH 4/4] Solution Implement trie prefix tree

---
 implement-trie-prefix-tree/doitduri.swift | 46 +++++++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 implement-trie-prefix-tree/doitduri.swift

diff --git a/implement-trie-prefix-tree/doitduri.swift b/implement-trie-prefix-tree/doitduri.swift
new file mode 100644
index 000000000..688add953
--- /dev/null
+++ b/implement-trie-prefix-tree/doitduri.swift
@@ -0,0 +1,46 @@
+class TrieNode {
+    var children: [Character: TrieNode] = [:]
+    var isEnd: Bool = false
+}
+
+class Trie {
+    private let root: TrieNode
+    
+    init() {
+        root = TrieNode()
+    }
+    
+    func insert(_ word: String) {
+        var current = root
+        for char in word {
+            if current.children[char] == nil {
+                current.children[char] = TrieNode()
+            }
+            current = current.children[char]!
+        }
+        current.isEnd = true
+    }
+    
+    func search(_ word: String) -> Bool {
+        guard let node = findNode(word) else {
+            return false
+        }
+        return node.isEnd
+    }
+    
+    func startsWith(_ prefix: String) -> Bool {
+        return findNode(prefix) != nil
+    }
+    
+    private func findNode(_ prefix: String) -> TrieNode? {
+        var current = root
+        for char in prefix {
+            guard let next = current.children[char] else {
+                return nil
+            }
+            current = next
+        }
+        return current
+    }
+}
+