diff --git a/problems/二叉树的统一迭代法.md b/problems/二叉树的统一迭代法.md index 8089af64..ad79424d 100644 --- a/problems/二叉树的统一迭代法.md +++ b/problems/二叉树的统一迭代法.md @@ -741,6 +741,99 @@ impl Solution{ } } ``` +### C# +```C# +// 前序遍历 +public IList PreorderTraversal(TreeNode root) +{ + var res = new List(); + var st = new Stack(); + if (root == null) return res; + st.Push(root); + while (st.Count != 0) + { + var node = st.Peek(); + if (node == null) + { + st.Pop(); + node = st.Peek(); + st.Pop(); + res.Add(node.val); + } + else + { + st.Pop(); + if (node.right != null) st.Push(node.right); + if (node.left != null) st.Push(node.left); + st.Push(node); + st.Push(null); + } + } + return res; +} +``` +```C# +// 中序遍历 +public IList InorderTraversal(TreeNode root) +{ + var res = new List(); + var st = new Stack(); + if (root == null) return res; + st.Push(root); + while (st.Count != 0) + { + var node = st.Peek(); + if (node == null) + { + st.Pop(); + node = st.Peek(); + st.Pop(); + res.Add(node.val); + } + else + { + st.Pop(); + if (node.right != null) st.Push(node.right); + st.Push(node); + st.Push(null); + if (node.left != null) st.Push(node.left); + } + } + return res; +} +``` + +```C# +// 后序遍历 +public IList PostorderTraversal(TreeNode root) +{ + var res = new List(); + var st = new Stack(); + if (root == null) return res; + st.Push(root); + while (st.Count != 0) + { + var node = st.Peek(); + if (node == null) + { + st.Pop(); + node = st.Peek(); + st.Pop(); + res.Add(node.val); + } + else + { + st.Pop(); + if (node.left != null) st.Push(node.left); + if (node.right != null) st.Push(node.right); + st.Push(node); + st.Push(null); + } + } + res.Reverse(0, res.Count); + return res; +} +```