199_Binary_Tree_Right_Side_View

Author: Partho Biswas

README.md

@@ -432,7 +432,7 @@ Check this [golden](https://tinyurl.com/ujopecz) post.
 |14| **[979. Distribute Coins in Binary Tree](https://leetcode.com/problems/distribute-coins-in-binary-tree/)**| [Python](https://tinyurl.com/wu6rdaw/979_Distribute_Coins_in_Binary_Tree.py)| [Art 1](https://tinyurl.com/rugoa38), [Art 2](https://tinyurl.com/whkdbl4), [Art 3](https://tinyurl.com/s62fws7) | Medium | **Very important. Postorder DFS** |
 |15| [116. Populating Next Right Pointers in Each Node](https://leetcode.com/problems/populating-next-right-pointers-in-each-node/)| [Python](https://tinyurl.com/wu6rdaw/116_Populating_Next_Right_Pointers_in_Each_Node.py)| [Art 1](https://tinyurl.com/t6p8kjb), [Art 2](https://tinyurl.com/ujzrhkj), **[Art 3](https://tinyurl.com/unrow77)** | Medium | BFS/DFS, Level order traversal |
 |16| [117. Populating Next Right Pointers in Each Node II](https://leetcode.com/problems/populating-next-right-pointers-in-each-node-ii/)| [Python](https://tinyurl.com/wu6rdaw/117_Populating_Next_Right_Pointers_in_Each_Node_II.py)| [Vid 1](https://tinyurl.com/rfjhzj3), [Vid 2](https://tinyurl.com/ryghj42) | Medium | **Very tricky, check again** |
-|17| [199. Binary Tree Right Side View](https://tinyurl.com/y65vxqj2)| [Python](https://tinyurl.com/wu6rdaw/199_Binary_Tree_Right_Side_View.py)| --- | Medium | --- |
+|17| [199. Binary Tree Right Side View](https://tinyurl.com/y65vxqj2)| [Python](https://tinyurl.com/wu6rdaw/199_Binary_Tree_Right_Side_View.py), [Swift](https://tinyurl.com/wuja3c4/199_Binary_Tree_Right_Side_View.swift) | --- | Medium | --- |
 |18| **[863. All Nodes Distance K in Binary Tree](https://tinyurl.com/w5dmj3o)**| [Python](https://tinyurl.com/wu6rdaw/863_All_Nodes_Distance_K_in_Binary_Tree.py)| [Vid 1](https://tinyurl.com/tn4ncqy), [Art 1](https://tinyurl.com/t3ozct3), [Art 2](https://tinyurl.com/rvbhznn) | Medium | A combination of graph and tree. TODO: Check again. Very important |
 |19| [301. Remove Invalid Parentheses](https://tinyurl.com/w9lfsgt) | [Python](https://tinyurl.com/wu6rdaw/301_Remove_Invalid_Parentheses.py)| [Vid 1](https://tinyurl.com/rbp6xa7), [Vid 2](https://tinyurl.com/sjk44du), [Art 1](https://tinyurl.com/tcglxfp) | Hard | TODO: Not done, Check again. Very important. BFS and DFS |
 |20| [112. Path Sum](https://tinyurl.com/rg6m7ua) | [Python](https://tinyurl.com/wu6rdaw/112_Path_Sum.py)| [Art 1](https://tinyurl.com/t2dggse) | Easy | --- |

leetcode.com/swift/DS_ALGO_PRAC.playground/Sources/swift/199_Binary_Tree_Right_Side_View.swift

@@ -0,0 +1,39 @@
+import Foundation
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     public var val: Int
+ *     public var left: TreeNode?
+ *     public var right: TreeNode?
+ *     public init() { self.val = 0; self.left = nil; self.right = nil; }
+ *     public init(_ val: Int) { self.val = val; self.left = nil; self.right = nil; }
+ *     public init(_ val: Int, _ left: TreeNode?, _ right: TreeNode?) {
+ *         self.val = val
+ *         self.left = left
+ *         self.right = right
+ *     }
+ * }
+ */
+class Solution {
+    func rightSideView(_ root: TreeNode?) -> [Int] {
+        guard var root = root else {
+            return []
+        }
+        var rightView = [Int]()
+        var (maxDepthSoFar, currentDepth) = (-1, -1)
+        rightSideViewDFSHelper(root, currentDepth + 1, &maxDepthSoFar, &rightView)
+        return rightView
+    }
+    
+    private func rightSideViewDFSHelper(_ root: TreeNode?, _ currentDepth: Int, _ maxDepthSoFar: inout Int, _ rightView: inout [Int]) {
+        guard var root = root else {
+            return
+        }
+        if currentDepth > maxDepthSoFar {
+            rightView.append(root.val)
+            maxDepthSoFar = currentDepth
+        }
+        rightSideViewDFSHelper(root.right, currentDepth + 1, &maxDepthSoFar, &rightView)
+        rightSideViewDFSHelper(root.left, currentDepth + 1, &maxDepthSoFar, &rightView)
+    }
+}