Trees: Binary Tree Right Side View

src/main/java/com/pallamsetty/trees/BinaryTreeRightSideView.java

@@ -0,0 +1,44 @@
+package com.pallamsetty.trees;
+
+/*
+* Leetcode 199
+* */
+
+import com.pallamsetty.trees.helpers.TreeNode;
+
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Queue;
+
+public class BinaryTreeRightSideView {
+    public List<Integer> getRightSideView(TreeNode root) {
+        if(root == null) {
+            return new ArrayList<>();
+        }
+        Queue<TreeNode> queue = new LinkedList<>();
+        queue.offer(root);
+        List<Integer> result = new ArrayList<>();
+
+        while(!queue.isEmpty()) {
+            int size = queue.size();
+
+            for(int i = 0; i < size; i++) {
+                TreeNode current = queue.poll();
+
+                if(i == size - 1) {
+                    result.add(current.val);
+                }
+
+                if(current.left != null) {
+                    queue.offer(current.left);
+                }
+
+                if(current.right != null) {
+                    queue.offer(current.right);
+                }
+            }
+        }
+        return result;
+    }
+}

src/test/java/com/pallamsetty/trees/BinaryTreeRightSideViewTest.java

@@ -0,0 +1,95 @@
+package com.pallamsetty.trees;
+
+import com.pallamsetty.trees.helpers.TreeNode;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.Assert.assertArrayEquals;
+
+public class BinaryTreeRightSideViewTest {
+    private final BinaryTreeRightSideView btrsv;
+
+    public BinaryTreeRightSideViewTest() {
+        btrsv = new BinaryTreeRightSideView();
+    }
+
+    @Test
+    public void testGetRightSideView1() {
+        TreeNode root = new TreeNode(1);
+        root.left = new TreeNode(2);
+        root.right = new TreeNode(3);
+
+        List<Integer> expected = Arrays.asList(new Integer[] {1, 3});
+        List<Integer> actual = btrsv.getRightSideView(root);
+
+        assertArrayEquals(expected.toArray(), actual.toArray());
+    }
+
+    @Test
+    public void testGetRightSideView2() {
+        TreeNode root = new TreeNode(1);
+        root.left = new TreeNode(2);
+        root.left.left = new TreeNode(4);
+        root.left.right = new TreeNode(5);
+        root.right = new TreeNode(3);
+        root.right.left = new TreeNode(6);
+        root.right.right = new TreeNode(7);
+
+        List<Integer> expected = Arrays.asList(new Integer[] {1, 3, 7});
+        List<Integer> actual = btrsv.getRightSideView(root);
+
+        assertArrayEquals(expected.toArray(), actual.toArray());
+    }
+
+    @Test
+    public void testGetRightSideView3() {
+        TreeNode root = new TreeNode(1);
+        root.left = new TreeNode(2);
+        root.left.right = new TreeNode(5);
+        root.right = new TreeNode(3);
+        root.right.right = new TreeNode(4);
+
+        List<Integer> expected = Arrays.asList(new Integer[] {1, 3, 4});
+        List<Integer> actual = btrsv.getRightSideView(root);
+
+        assertArrayEquals(expected.toArray(), actual.toArray());
+    }
+
+    @Test
+    public void testGetRightSideView4() {
+        TreeNode root = new TreeNode(1);
+        root.left = new TreeNode(2);
+        root.left.left = new TreeNode(4);
+        root.right = new TreeNode(3);
+        root.left.left.left = new TreeNode(5);
+
+        List<Integer> expected = Arrays.asList(new Integer[] {1, 3, 4, 5});
+        List<Integer> actual = btrsv.getRightSideView(root);
+
+        assertArrayEquals(expected.toArray(), actual.toArray());
+    }
+
+    @Test
+    public void testGetRightSideView5() {
+        TreeNode root = new TreeNode(1);
+        root.right = new TreeNode(3);
+
+        List<Integer> expected = Arrays.asList(new Integer[] {1, 3});
+        List<Integer> actual = btrsv.getRightSideView(root);
+
+        assertArrayEquals(expected.toArray(), actual.toArray());
+    }
+
+    @Test
+    public void testGetRightSideView6() {
+        TreeNode root = null;
+
+        List<Integer> expected = new ArrayList<>();
+        List<Integer> actual = btrsv.getRightSideView(root);
+
+        assertArrayEquals(expected.toArray(), actual.toArray());
+    }
+}