Added problem 199

Author: mkhuzaima

0199_Binary_Tree_Right_Side_View.java

@@ -0,0 +1,37 @@
+// id: 199
+// Name: Binary Tree Right Side View
+// link: https://leetcode.com/problems/binary-tree-right-side-view/
+// Difficulty: Medium
+
+class Solution {
+    public List<Integer> rightSideView(TreeNode root) {
+        // right side view means the rightmost element of each level
+
+        List<Integer> result = new ArrayList<>();
+
+        Queue<TreeNode> q = new LinkedList<>();
+        if (root != null) {
+            q.add(root);
+        }
+
+        while (!q.isEmpty()) {
+            int count = q.size();
+            // traverse the complete level
+            while (count > 0) {
+                root = q.poll();
+
+                if (root.left != null) {
+                    q.add(root.left);
+                }
+                if (root.right != null) {
+                    q.add(root.right);
+                }
+                count--;
+            }
+            // add the last level to the result
+            result.add(root.val);
+        }
+
+        return result;
+    }
+}