public List<List<Integer>> zigzagLevelOrder(TreeNode root) {
List<List<Integer>> result = new ArrayList<>();
if (root == null) {
return result;
}
Queue<TreeNode> queue = new LinkedList<TreeNode>();
queue.offer(root);
boolean flagOdd = true;
while (!queue.isEmpty()) {
int qsize = queue.size();
List<Integer> subResult = new ArrayList<Integer>();
for (int i = 0; i < qsize; i++) {
TreeNode node = queue.poll();
subResult.add(node.val);
if (node.left != null) {
queue.offer(node.left);
}
if (node.right != null) {
queue.offer(node.right);
}
}
if (flagOdd) {
result.add(subResult);
} else {
Collections.reverse(subResult);
result.add(subResult);
}
flagOdd = !flagOdd;
}
return result;
}
public List<List<Integer>> levelOrderBottom(TreeNode root) {
List<List<Integer>> ret = new ArrayList();
if (root == null) return ret;
helper(ret, root, 1);
Collections.reverse(ret);
return ret;
}
/**
* @param root: The root of binary tree.
* @return: buttom-up level order a list of lists of integer
*/
public ArrayList<ArrayList<Integer>> levelOrderBottom(TreeNode root) {
// write your code here
Queue<TreeNode> q = new LinkedList<TreeNode>();
ArrayList<ArrayList<Integer>> res = new ArrayList<ArrayList<Integer>>();
if (root == null) return res;
q.add(root);
while (!q.isEmpty()) {
ArrayList<Integer> cur = new ArrayList<Integer>();
int size = q.size();
for (int i = 0; i < size; i++) {
TreeNode temp = q.poll();
cur.add(temp.val);
if (temp.left != null) q.add(temp.left);
if (temp.right != null) q.add(temp.right);
}
res.add(cur);
}
Collections.reverse(res);
return res;
}
// @RubyLevelMethod(name="reverse!")
public RubyArray reverseBang() {
Collections.reverse(array_);
return this;
}
// @RubyLevelMethod(name="reverse")
public RubyArray reverse() {
RubyArray array = this.copy();
Collections.reverse(array.array_);
return array;
}