Create 199-Binary-Tree-Right-Side-View.cs

Author: notauserx

csharp/199-Binary-Tree-Right-Side-View.cs

@@ -0,0 +1,45 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     public int val;
+ *     public TreeNode left;
+ *     public TreeNode right;
+ *     public TreeNode(int val=0, TreeNode left=null, TreeNode right=null) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */
+public class Solution {
+    public IList<int> RightSideView(TreeNode root) {
+        var result = new List<int>();
+        if(root == null) 
+            return result;
+        var q = new Queue<TreeNode>();
+        q.Enqueue(root);
+        
+        // traverse the tree using BFS
+        while(true) {
+            var count = q.Count;
+            if(count == 0) break;
+            
+            for(var i = 0; i < count; i++) {
+                var cur = q. Dequeue();
+                
+                if(cur.left != null)
+                    q.Enqueue(cur.left);
+                if(cur.right != null) 
+                    q.Enqueue(cur.right);
+                
+                
+                // only add the last node from each level, i.e the rightmost node
+                if(i == count - 1) {
+                    result.Add(cur.val);
+                }
+            }
+        }
+        
+        return result;
+    }
+}