[cousins && rightSideView]

CousinNodes.java

@@ -0,0 +1,42 @@
+// Time: O(n)
+// Space: O(n)
+// Ran succesfully on Leetcode: yes
+class Solution {
+    public boolean isCousins(TreeNode root, int x, int y) {
+        // initialize queue
+        Queue<TreeNode> q = new LinkedList<>();
+        q.add(root);
+
+        while (!q.isEmpty()) {
+            // reinitialize present for every level
+            int size = q.size();
+            boolean x_present = false;
+            boolean y_present = false;
+            // iterate over the snapshot for the level by level
+            for (int i = 0; i < size; i++) {
+
+                TreeNode curr = q.poll();
+                // if same parent then siblings
+                if (curr.left != null && curr.right != null) {
+                    if ((curr.left.val == x && curr.right.val == y) ||
+                            (curr.left.val == y && curr.right.val == x)) {
+
+                        return false;
+                    }
+                }
+
+                if (curr.val == x) x_present = true;
+                if (curr.val == y) y_present = true;
+
+                if (curr.left != null) q.add(curr.left);
+                if (curr.right != null) q.add(curr.right);
+            }
+            // for each level finally check if both are present
+            if (x_present && y_present) return true;
+            if (x_present || y_present) return false;
+        }
+
+        return false;
+    }
+
+}

RightSideView.java

@@ -0,0 +1,31 @@
+// TimeComplexity: O(n)
+// SpaceComplexity: O(W)
+// Ran succesfully on Leetcode: yes
+class Solution {
+    public List<Integer> rightSideView(TreeNode root) {
+        List<Integer> list = new ArrayList<>();
+        if (root == null) return list;
+        // initialize queue
+        Queue<TreeNode> q = new LinkedList<>();
+        q.add(root);
+        int size = q.size();
+
+        while (!q.isEmpty()) {
+            TreeNode curr = q.poll();
+            size--;
+            if (curr.left != null) {
+                q.add(curr.left);
+            }
+            if (curr.right != null) {
+                q.add(curr.right);
+            }
+            // take new size snapshot of the queue and add right most val for the level
+            if (size == 0) {
+                size = q.size();
+                list.add(curr.val);
+            }
+        }
+        return list;
+
+    }
+}