leetcode/Problem107.java at master · actor168/leetcode · GitHub

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importjava.util.ArrayList;
importjava.util.List;

classProblem107 {

publicstaticvoidmain(String[] args) {
Problem107p = newProblem107();

TreeNoderoot = newTreeNode(1);/*
 root.left = new TreeNode(2);
 root.right = new TreeNode(3);
 root.left.left = new TreeNode(4);
 root.left.right = new TreeNode(5);
 root.right.left = new TreeNode(6);
 root.right.right = new TreeNode(7);
 root.left.left.left = new TreeNode(8);
 root.left.left.right = new TreeNode(9);
 root.right.left.left = new TreeNode(10);
 root.right.left.right = new TreeNode(11);
 root.right.right.right = new TreeNode(12);*/
System.out.println(p.levelOrderBottom(root));
 }

publicList<List<Integer>> levelOrderBottom(TreeNoderoot) {
if (root == null) {
returnnewArrayList<List<Integer>>();
 }
List<TreeNode> nodes = newArrayList<>();
nodes.add(root);
List<List<Integer>> integers = newArrayList<>();
List<Integer> res1 = traverse(nodes, integers);

if (res1.size() > 0) {
integers.add(res1);
 }

//add root
List<Integer> res2 = newArrayList<>();
res2.add(root.val);

integers.add(res2);
returnintegers;
 }

List<Integer> traverse(List<TreeNode> nodes, List<List<Integer>> res) {
List<TreeNode> subNodes = newArrayList<>();
List<Integer> integers = newArrayList<>();
if (nodes.size() <= 0 || nodes == null) {
returnintegers;
 }
for (TreeNodevar : nodes) {
if (var.left != null) {
subNodes.add(var.left);
integers.add(var.left.val);
 }

if (var.right != null) {
subNodes.add(var.right);
integers.add(var.right.val);
 }
 }
List<Integer> vals = traverse(subNodes, res);
if (vals.size() > 0) res.add(vals);
returnintegers;
 }

}