From 5ed99e8319e20593b32bb23467df10b300b01355 Mon Sep 17 00:00:00 2001
From: abc <>
Date: Tue, 22 Jul 2025 22:00:20 +0900
Subject: [PATCH 01/12] two sum solution

---
 two-sum/SeongA.swift | 13 +++++++++++++
 1 file changed, 13 insertions(+)
 create mode 100644 two-sum/SeongA.swift

diff --git a/two-sum/SeongA.swift b/two-sum/SeongA.swift
new file mode 100644
index 000000000..423ece945
--- /dev/null
+++ b/two-sum/SeongA.swift
@@ -0,0 +1,13 @@
+class Solution {
+    func twoSum(_ nums: [Int], _ target: Int) -> [Int] {
+        var dictionary: [Int: Int] = [:]
+        for (index, value) in nums.enumerated() {
+            let difference = target - value
+            if let otherIndex = dictionary[difference] {
+                return [otherIndex, index]
+            }
+            dictionary[value] = index
+        }
+        return []
+    }
+}

From 751a88128a38363493a98fb05b759da8a1454688 Mon Sep 17 00:00:00 2001
From: delight010 <seonga.oh00@gmail.com>
Date: Tue, 22 Jul 2025 22:29:52 +0900
Subject: [PATCH 02/12] Add line Two Sum solution

---
 two-sum/SeongA.swift | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/two-sum/SeongA.swift b/two-sum/SeongA.swift
index 423ece945..cfcc1adab 100644
--- a/two-sum/SeongA.swift
+++ b/two-sum/SeongA.swift
@@ -11,3 +11,6 @@ class Solution {
         return []
     }
 }
+ 
+
+

From 98bc154d26110c16bbe3474323a269548c0963ad Mon Sep 17 00:00:00 2001
From: SeongA <81559026+delight010@users.noreply.github.com>
Date: Tue, 22 Jul 2025 22:31:20 +0900
Subject: [PATCH 03/12] Update SeongA.swift

---
 two-sum/SeongA.swift | 2 --
 1 file changed, 2 deletions(-)

diff --git a/two-sum/SeongA.swift b/two-sum/SeongA.swift
index cfcc1adab..16a2ece77 100644
--- a/two-sum/SeongA.swift
+++ b/two-sum/SeongA.swift
@@ -12,5 +12,3 @@ class Solution {
     }
 }
  
-
-

From c520c8415a4770a169d2429fe530e2fab44a30c6 Mon Sep 17 00:00:00 2001
From: SeongA <81559026+delight010@users.noreply.github.com>
Date: Tue, 22 Jul 2025 22:32:13 +0900
Subject: [PATCH 04/12] Update SeongA.swift


From c317868ab71441400207acb244e83ed69e87b55e Mon Sep 17 00:00:00 2001
From: SeongA <81559026+delight010@users.noreply.github.com>
Date: Tue, 22 Jul 2025 22:35:26 +0900
Subject: [PATCH 05/12] Rename SeongA.swift to delight010.swift

---
 two-sum/{SeongA.swift => delight010.swift} | 0
 1 file changed, 0 insertions(+), 0 deletions(-)
 rename two-sum/{SeongA.swift => delight010.swift} (100%)

diff --git a/two-sum/SeongA.swift b/two-sum/delight010.swift
similarity index 100%
rename from two-sum/SeongA.swift
rename to two-sum/delight010.swift

From 33aca2b36094896ab2d41a58722535b5afd65f1c Mon Sep 17 00:00:00 2001
From: delight010 <seonga.oh00@gmail.com>
Date: Thu, 24 Jul 2025 21:34:39 +0900
Subject: [PATCH 06/12] contains duplicate

---
 contains-duplicate/delight010.swift | 13 +++++++++++++
 1 file changed, 13 insertions(+)
 create mode 100644 contains-duplicate/delight010.swift

diff --git a/contains-duplicate/delight010.swift b/contains-duplicate/delight010.swift
new file mode 100644
index 000000000..683d7d20f
--- /dev/null
+++ b/contains-duplicate/delight010.swift
@@ -0,0 +1,13 @@
+class Solution {
+    func containsDuplicate(_ nums: [Int]) -> Bool {
+        var dictionary: [Int: Int] = [:]
+        for (index, num) in nums.enumerated() {
+            if let value = dictionary[num], value != index {
+                return true
+            }
+            dictionary[num] = index
+        }
+        return false
+    }
+}
+ 

From b2b77925f51da6c685732256871ede3955b22879 Mon Sep 17 00:00:00 2001
From: delight010 <seonga.oh00@gmail.com>
Date: Thu, 24 Jul 2025 23:14:50 +0900
Subject: [PATCH 07/12] top k frequent elements

---
 top-k-frequent-elements/delight010.swift | 11 +++++++++++
 1 file changed, 11 insertions(+)
 create mode 100644 top-k-frequent-elements/delight010.swift

diff --git a/top-k-frequent-elements/delight010.swift b/top-k-frequent-elements/delight010.swift
new file mode 100644
index 000000000..68ae04723
--- /dev/null
+++ b/top-k-frequent-elements/delight010.swift
@@ -0,0 +1,11 @@
+class Solution {
+    func topKFrequent(_ nums: [Int], _ k: Int) -> [Int] {
+        var dictionary: [Int: Int] = [:]
+        for num in nums {
+            dictionary[num, default: 0] += 1
+        }
+        
+        return dictionary.sorted(by: { $0.value > $1.value }).prefix(k).map(\.key)
+    }
+}
+ 

From ffaa6d8f6bc6807a7589ce4fe3644d2fa1c0da46 Mon Sep 17 00:00:00 2001
From: delight010 <seonga.oh00@gmail.com>
Date: Thu, 24 Jul 2025 23:22:14 +0900
Subject: [PATCH 08/12] Add comments to top-k-frequent-element

---
 top-k-frequent-elements/delight010.swift | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/top-k-frequent-elements/delight010.swift b/top-k-frequent-elements/delight010.swift
index 68ae04723..bd4e2248a 100644
--- a/top-k-frequent-elements/delight010.swift
+++ b/top-k-frequent-elements/delight010.swift
@@ -1,11 +1,19 @@
 class Solution {
     func topKFrequent(_ nums: [Int], _ k: Int) -> [Int] {
         var dictionary: [Int: Int] = [:]
-        for num in nums {
+        for num in nums { // for loop를 돌면서 O(n)의 시간복잡도
             dictionary[num, default: 0] += 1
+            // Swift에서 dictionary 검색의 시간복잡도는 O(1)
         }
         
-        return dictionary.sorted(by: { $0.value > $1.value }).prefix(k).map(\.key)
+        return dictionary
+            .sorted(by: { $0.value > $1.value })
+        // dictionary sorted()의 시간복잡도 O(n log n)
+            .prefix(k)
+        // k의 개수만큼 탐색합니다. 고로 시간복잡도는 O(n)
+            .map(\.key)
+        // prefix에서 k만큼 탐색하였습니다.
+        // .map의 시간복잡도는 O(n)입니다.
     }
 }
  

From 0d7e8da1b65a515b175889c87701869a188d35b4 Mon Sep 17 00:00:00 2001
From: delight010 <seonga.oh00@gmail.com>
Date: Thu, 24 Jul 2025 23:25:09 +0900
Subject: [PATCH 09/12] Add comment to two-sum

---
 two-sum/delight010.swift | 1 +
 1 file changed, 1 insertion(+)

diff --git a/two-sum/delight010.swift b/two-sum/delight010.swift
index 16a2ece77..b08201145 100644
--- a/two-sum/delight010.swift
+++ b/two-sum/delight010.swift
@@ -2,6 +2,7 @@ class Solution {
     func twoSum(_ nums: [Int], _ target: Int) -> [Int] {
         var dictionary: [Int: Int] = [:]
         for (index, value) in nums.enumerated() {
+            // nums배열의 개수만큼 반복합니다. O(n)
             let difference = target - value
             if let otherIndex = dictionary[difference] {
                 return [otherIndex, index]

From ad607f497ad355deeb69240fbb2aa0328edc90d1 Mon Sep 17 00:00:00 2001
From: delight010 <seonga.oh00@gmail.com>
Date: Thu, 24 Jul 2025 23:27:47 +0900
Subject: [PATCH 10/12] Add comments to contains-duplicate

---
 contains-duplicate/delight010.swift | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/contains-duplicate/delight010.swift b/contains-duplicate/delight010.swift
index 683d7d20f..9b3889bbe 100644
--- a/contains-duplicate/delight010.swift
+++ b/contains-duplicate/delight010.swift
@@ -2,8 +2,11 @@ class Solution {
     func containsDuplicate(_ nums: [Int]) -> Bool {
         var dictionary: [Int: Int] = [:]
         for (index, num) in nums.enumerated() {
+            // 배열 nums의 개수만큼 반복합니다. 시간복잡도 O(n)
             if let value = dictionary[num], value != index {
                 return true
+                // 만일 동일한 숫자를 일찍 찾게 된다면
+                // 시간복잡도는 O(n)보다 더 빨라질 수 있습니다.
             }
             dictionary[num] = index
         }

From d7bf9b62a680308d9f885a73538c04773e57977f Mon Sep 17 00:00:00 2001
From: delight010 <seonga.oh00@gmail.com>
Date: Fri, 25 Jul 2025 14:17:28 +0900
Subject: [PATCH 11/12] solve longest consecutive sequence

---
 longest-consecutive-sequence/delight010.swift | 26 +++++++++++++++++++
 1 file changed, 26 insertions(+)
 create mode 100644 longest-consecutive-sequence/delight010.swift

diff --git a/longest-consecutive-sequence/delight010.swift b/longest-consecutive-sequence/delight010.swift
new file mode 100644
index 000000000..dbed046f8
--- /dev/null
+++ b/longest-consecutive-sequence/delight010.swift
@@ -0,0 +1,26 @@
+class Solution {
+    func longestConsecutive(_ nums: [Int]) -> Int {
+        if nums.isEmpty { return 0 }
+        // .isEmpty 메서드를 사용하여 배열의 개수가 0일 시 바로 0을 리턴합니다.
+        // 시간복잡도 O(1)
+        var maxCount = 0
+        var count = 1
+        var prefixNumber = nums.sorted().first ?? 0
+        for num in nums.sorted(by: <) {
+            // nums 배열을 오름차순 정리 후 반복문을 루프합니다.
+            // .sorted 시간복잡도 O(n log n)
+            // for문 시간복잡도 O(n)
+            if prefixNumber == num {
+                continue
+            } else if prefixNumber + 1 == num {
+                count += 1
+                prefixNumber = num
+            } else {
+                maxCount = max(maxCount, count)
+                count = 1
+                prefixNumber = num
+            }
+        }
+        return max(maxCount, count)
+    }
+}

From 37b336c6f64e14330fcbbdc48c6da7dd6de3b1c1 Mon Sep 17 00:00:00 2001
From: delight010 <seonga.oh00@gmail.com>
Date: Fri, 25 Jul 2025 19:38:24 +0900
Subject: [PATCH 12/12] solve house robber

---
 house-robber/delight010.swift | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
 create mode 100644 house-robber/delight010.swift

diff --git a/house-robber/delight010.swift b/house-robber/delight010.swift
new file mode 100644
index 000000000..6452868c7
--- /dev/null
+++ b/house-robber/delight010.swift
@@ -0,0 +1,15 @@
+class Solution {
+    func rob(_ nums: [Int]) -> Int {
+        var sum1 = 0
+        var sum2 = 0
+        for num in nums {
+            // for문을 통해 루프.
+            // 시간복잡도는 O(n)
+            let temp = max(num + sum1, sum2)
+            sum1 = sum2
+            sum2 = temp
+        }
+        return sum2
+    }
+}
+