import org.junit.Assert;

import org.junit.Test;

import java.util.Arrays;

import java.util.Collections;

public class BinaryTreeLevelOrderTraversalIITest {

@Test

public void testLevelOrderBottom() {

BinaryTreeLevelOrderTraversalII b = new BinaryTreeLevelOrderTraversalII();

Assert.assertTrue(b.levelOrderBottom(null).isEmpty());

BinaryTreeLevelOrderTraversalII.TreeNode node0 = new BinaryTreeLevelOrderTraversalII.TreeNode(1);

Assert.assertEquals(b.levelOrderBottom(node0), Collections.singletonList(Collections.singletonList(1)));

BinaryTreeLevelOrderTraversalII.TreeNode node1 = new BinaryTreeLevelOrderTraversalII.TreeNode(3);

node1.left = new BinaryTreeLevelOrderTraversalII.TreeNode(9);

node1.right = new BinaryTreeLevelOrderTraversalII.TreeNode(20);

node1.right.left = new BinaryTreeLevelOrderTraversalII.TreeNode(15);

node1.right.right = new BinaryTreeLevelOrderTraversalII.TreeNode(7);

Assert.assertEquals(b.levelOrderBottom(node1), Arrays.asList(Arrays.asList(15, 7), Arrays.asList(9, 20), Collections.singletonList(3)));

}

}