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BinaryTreeZigZagTraversal.java
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71 lines (58 loc) · 2.04 KB
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package Leetcode;
import java.util.ArrayList;
import java.util.List;
import java.util.Stack;
public class BinaryTreeZigZagTraversal
{
public List<List<Integer>> zigzagLevelOrder(TreeNode root) {
List<List<Integer>> result = new ArrayList();
boolean rightToLeft = false;
Stack<TreeNode> stack1 = new Stack();
Stack<TreeNode> stack2 = new Stack();
stack1.push(root);
result.add(new ArrayList());
while(!stack1.isEmpty())
{
TreeNode temp = stack1.pop();
result.get(result.size()-1).add(temp.val);
if( temp!=null)
{
if(rightToLeft)
{
if(temp.left!=null)
stack2.push(temp.left);
if(temp.right!=null)
stack2.push(temp.right);
}
else
{
if(temp.right!=null)
stack2.push(temp.right);
if(temp.left!=null)
stack2.push(temp.left);
}
}
if(stack1.isEmpty())
{
result.add(new ArrayList());
rightToLeft = !rightToLeft;
Stack<TreeNode> temp1 = stack2;
stack2 = stack1;
stack1 = temp1;
}
}
return result;
}
public static void main( String[] args )
{
BinaryTreeZigZagTraversal obj = new BinaryTreeZigZagTraversal();
TreeNode root = new TreeNode(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);
List<List<Integer>> zigzagLevelOrder = obj.zigzagLevelOrder( root );
}
}