LeetCode基础--二叉树--中序遍历

public class Solution {
public IList<int> PreorderTraversal(TreeNode root) {
List<int> result = new List<int>();
if (root != null){
result.AddRange(PreorderTraversal(root.left));
result.Add(root.val);
result.AddRange(PreorderTraversal(root.right));
}
return result;
}
}

public class Solution {
public IList<int> InorderTraversal(TreeNode root) {
List<int> result = new List<int>();
if(root == null)
{
return result;
}

Stack<TreeNode> stack = new Stack<TreeNode>();
TreeNode runNode = root;
while(runNode != null || stack.Count > 0)
{
if(runNode != null)
{
stack.Push(runNode);
runNode = runNode.left;
}
else
{
runNode = stack.Peek();
result.Add(stack.Pop().val);
runNode = runNode.right;
}

}

return result;
}
}