From 5178f3b530ba3654bf5dd8d487aa3cea949b2448 Mon Sep 17 00:00:00 2001
From: Lanre Adedara <lanre.adedara@shara.co>
Date: Wed, 24 Apr 2024 09:02:00 +0100
Subject: [PATCH 1/2] Swift Implementation for LCCI 04.04

---
 lcci/04.04.Check Balance/README.md      | 34 +++++++++++++++++++++++++
 lcci/04.04.Check Balance/README_EN.md   | 34 +++++++++++++++++++++++++
 lcci/04.04.Check Balance/Solution.swift | 31 ++++++++++++++++++++++
 3 files changed, 99 insertions(+)
 create mode 100644 lcci/04.04.Check Balance/Solution.swift

diff --git a/lcci/04.04.Check Balance/README.md b/lcci/04.04.Check Balance/README.md
index fd20dab40c0dc..a699c8a5ee0ab 100644
--- a/lcci/04.04.Check Balance/README.md	
+++ b/lcci/04.04.Check Balance/README.md	
@@ -167,6 +167,40 @@ function isBalanced(root: TreeNode | null): boolean {
 }
 ```
 
+```swift
+/* class TreeNode {
+*    var val: Int
+*    var left: TreeNode?
+*    var right: TreeNode?
+*    
+*    init(_ val: Int) {
+*        self.val = val
+*        self.left = nil
+*        self.right = nil
+*    }
+*  } 
+*/
+
+class Solution {
+    func isBalanced(_ root: TreeNode?) -> Bool {
+        return dfs(root) >= 0
+    }
+
+    private func dfs(_ root: TreeNode?) -> Int {
+        guard let root = root else {
+            return 0
+        }
+
+        let leftHeight = dfs(root.left)
+        let rightHeight = dfs(root.right)
+        if leftHeight < 0 || rightHeight < 0 || abs(leftHeight - rightHeight) > 1 {
+            return -1
+        }
+        return max(leftHeight, rightHeight) + 1
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- end -->
diff --git a/lcci/04.04.Check Balance/README_EN.md b/lcci/04.04.Check Balance/README_EN.md
index 4a08d7f82d7ee..5d6e2de6459a5 100644
--- a/lcci/04.04.Check Balance/README_EN.md	
+++ b/lcci/04.04.Check Balance/README_EN.md	
@@ -210,6 +210,40 @@ function isBalanced(root: TreeNode | null): boolean {
 }
 ```
 
+```swift
+/* class TreeNode {
+*    var val: Int
+*    var left: TreeNode?
+*    var right: TreeNode?
+*    
+*    init(_ val: Int) {
+*        self.val = val
+*        self.left = nil
+*        self.right = nil
+*    }
+*  } 
+*/
+
+class Solution {
+    func isBalanced(_ root: TreeNode?) -> Bool {
+        return dfs(root) >= 0
+    }
+
+    private func dfs(_ root: TreeNode?) -> Int {
+        guard let root = root else {
+            return 0
+        }
+
+        let leftHeight = dfs(root.left)
+        let rightHeight = dfs(root.right)
+        if leftHeight < 0 || rightHeight < 0 || abs(leftHeight - rightHeight) > 1 {
+            return -1
+        }
+        return max(leftHeight, rightHeight) + 1
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- end -->
diff --git a/lcci/04.04.Check Balance/Solution.swift b/lcci/04.04.Check Balance/Solution.swift
new file mode 100644
index 0000000000000..b667b42ae3486
--- /dev/null
+++ b/lcci/04.04.Check Balance/Solution.swift	
@@ -0,0 +1,31 @@
+/* class TreeNode {
+*    var val: Int
+*    var left: TreeNode?
+*    var right: TreeNode?
+*    
+*    init(_ val: Int) {
+*        self.val = val
+*        self.left = nil
+*        self.right = nil
+*    }
+*  } 
+*/
+
+class Solution {
+    func isBalanced(_ root: TreeNode?) -> Bool {
+        return dfs(root) >= 0
+    }
+
+    private func dfs(_ root: TreeNode?) -> Int {
+        guard let root = root else {
+            return 0
+        }
+
+        let leftHeight = dfs(root.left)
+        let rightHeight = dfs(root.right)
+        if leftHeight < 0 || rightHeight < 0 || abs(leftHeight - rightHeight) > 1 {
+            return -1
+        }
+        return max(leftHeight, rightHeight) + 1
+    }
+}
\ No newline at end of file

From f8b57ec4bf0cf63ab78944fcf6b11f2c15fb9af7 Mon Sep 17 00:00:00 2001
From: klever34 <klever34@users.noreply.github.com>
Date: Wed, 24 Apr 2024 08:06:20 +0000
Subject: [PATCH 2/2] style: format code and docs with prettier

---
 lcci/04.04.Check Balance/README.md    | 4 ++--
 lcci/04.04.Check Balance/README_EN.md | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/lcci/04.04.Check Balance/README.md b/lcci/04.04.Check Balance/README.md
index a699c8a5ee0ab..1f8900aa27bbe 100644
--- a/lcci/04.04.Check Balance/README.md	
+++ b/lcci/04.04.Check Balance/README.md	
@@ -172,13 +172,13 @@ function isBalanced(root: TreeNode | null): boolean {
 *    var val: Int
 *    var left: TreeNode?
 *    var right: TreeNode?
-*    
+*
 *    init(_ val: Int) {
 *        self.val = val
 *        self.left = nil
 *        self.right = nil
 *    }
-*  } 
+*  }
 */
 
 class Solution {
diff --git a/lcci/04.04.Check Balance/README_EN.md b/lcci/04.04.Check Balance/README_EN.md
index 5d6e2de6459a5..ab6a2416cc2d2 100644
--- a/lcci/04.04.Check Balance/README_EN.md	
+++ b/lcci/04.04.Check Balance/README_EN.md	
@@ -215,13 +215,13 @@ function isBalanced(root: TreeNode | null): boolean {
 *    var val: Int
 *    var left: TreeNode?
 *    var right: TreeNode?
-*    
+*
 *    init(_ val: Int) {
 *        self.val = val
 *        self.left = nil
 *        self.right = nil
 *    }
-*  } 
+*  }
 */
 
 class Solution {