1. 二叉树结构：
代码
public class TwoXTree
{
public string Data { set; get; }
public TwoXTree LeftChild { set; get; }
public TwoXTree RightChild { set; get; }
public TwoXTree()
{
}
}
{
public string Data { set; get; }
public TwoXTree LeftChild { set; get; }
public TwoXTree RightChild { set; get; }
public TwoXTree()
{
}
}
2. 创建（这里直接通过输入广义表字符串来实现，为了简单起见，这里将Data域类型设置为char）：
代码
/// <summary>
/// Create a 2XTree
/// </summary>
/// <param name="treeString">eg: A(B(C,D),E(,F(G,)))$</param>
/// <returns></returns>
public static TwoXTree CreateTwoXTree(string treeString)
{
if (String.IsNullOrEmpty(treeString) || treeString.Equals("$"))
{
return null;
}
var charArray = treeString.ToCharArray();
if (charArray.Count(item => item == '(') != charArray.Count(item => item == ')'))
{
throw new ArgumentException("treeString");
}
Stack<TwoXTree> stack = new Stack<TwoXTree>();
TwoXTree root = new TwoXTree
{
Data = treeString[0].ToString()
};
stack.Push(root);
TwoXTree parent = root, node = root;
bool isLeftNode = true;
for (int i = 1; i < treeString.Length; i++)
{
switch (treeString[i])
{
case '$':
break;
case '(':
stack.Push(node);
parent = node;
isLeftNode = true;
break;
case ')':
stack.Pop();
parent = stack.Peek();
break;
case ',':
isLeftNode = false;
break;
default:
node = new TwoXTree
{
Data = treeString[i].ToString()
};
if (parent != null)
{
if (isLeftNode)
{
parent.LeftChild = node;
}
else
{
parent.RightChild = node;
}
}
break;
}
}
return root;
}
/// Create a 2XTree
/// </summary>
/// <param name="treeString">eg: A(B(C,D),E(,F(G,)))$</param>
/// <returns></returns>
public static TwoXTree CreateTwoXTree(string treeString)
{
if (String.IsNullOrEmpty(treeString) || treeString.Equals("$"))
{
return null;
}
var charArray = treeString.ToCharArray();
if (charArray.Count(item => item == '(') != charArray.Count(item => item == ')'))
{
throw new ArgumentException("treeString");
}
Stack<TwoXTree> stack = new Stack<TwoXTree>();
TwoXTree root = new TwoXTree
{
Data = treeString[0].ToString()
};
stack.Push(root);
TwoXTree parent = root, node = root;
bool isLeftNode = true;
for (int i = 1; i < treeString.Length; i++)
{
switch (treeString[i])
{
case '$':
break;
case '(':
stack.Push(node);
parent = node;
isLeftNode = true;
break;
case ')':
stack.Pop();
parent = stack.Peek();
break;
case ',':
isLeftNode = false;
break;
default:
node = new TwoXTree
{
Data = treeString[i].ToString()
};
if (parent != null)
{
if (isLeftNode)
{
parent.LeftChild = node;
}
else
{
parent.RightChild = node;
}
}
break;
}
}
return root;
}
3. 遍历：
代码
private void Visit(TwoXTree treeNode)
{
if (treeNode == null)
return;
Console.Write(" ---> {0} ", treeNode.Data);
}
#region Preorder traversal
public void Preorder_Recursion()
{
Visit(this);
if (this.LeftChild != null)
{
this.LeftChild.Preorder_Recursion();
}
if (this.RightChild != null)
{
this.RightChild.Preorder_Recursion();
}
}
public void Preorder()
{
Stack<TwoXTree> stack = new Stack<TwoXTree>();
Stack<bool> stack2 = new Stack<bool>();
TwoXTree node = this;
bool flag; // used to check if already visit both the left child and the right child of current node
do
{
while (node != null)
{
Visit(node);
stack.Push(node);
stack2.Push(false);
node = node.LeftChild;
}
node = stack.Pop();
flag = stack2.Pop();
if (flag)
{
node = null;
}
else
{
stack.Push(node);
stack2.Push(true);
node = node.RightChild;
}
} while (node != null || stack.Count > 0);
}
#endregion
#region Inorder
public void Inorder_Recursion()
{
if (this.LeftChild != null)
{
this.LeftChild.Inorder_Recursion();
}
Visit(this);
if (this.RightChild != null)
{
this.RightChild.Inorder_Recursion();
}
}
public void Inorder()
{
Stack<TwoXTree> stack = new Stack<TwoXTree>();
Stack<bool> stack2 = new Stack<bool>();
TwoXTree node = this;
bool flag;
do
{
while (node != null)
{
stack.Push(node);
stack2.Push(false);
node = node.LeftChild;
}
node = stack.Pop();
flag = stack2.Pop();
if (flag)
{
node = null;
}
else
{
Visit(node);
stack.Push(node);
stack2.Push(true);
node = node.RightChild;
}
} while (node != null || stack.Count > 0);
}
#endregion
#region Posorder
public void Posorder_Recursion()
{
if (this.LeftChild != null)
{
this.LeftChild.Posorder_Recursion();
}
if (this.RightChild != null)
{
this.RightChild.Posorder_Recursion();
}
Visit(this);
}
public void Posorder()
{
Stack<TwoXTree> stack = new Stack<TwoXTree>();
Stack<bool> stack2 = new Stack<bool>();
TwoXTree node = this;
bool flag;
do
{
while (node != null)
{
stack.Push(node);
stack2.Push(false);
node = node.LeftChild;
}
node = stack.Pop();
flag = stack2.Pop();
if (flag)
{
Visit(node);
node = null;
}
else
{
stack.Push(node);
stack2.Push(true);
node = node.RightChild;
}
} while (node != null || stack.Count > 0);
}
#endregion
#region Layer Order
public void LayerOrder()
{
Queue<TwoXTree> queue = new Queue<TwoXTree>();
queue.Enqueue(this);
TwoXTree node;
while (queue.Count > 0)
{
node = queue.Dequeue();
Visit(node);
if (node.LeftChild != null)
queue.Enqueue(node.LeftChild);
if (node.RightChild != null)
queue.Enqueue(node.RightChild);
}
}
#endregion
{
if (treeNode == null)
return;
Console.Write(" ---> {0} ", treeNode.Data);
}
#region Preorder traversal
public void Preorder_Recursion()
{
Visit(this);
if (this.LeftChild != null)
{
this.LeftChild.Preorder_Recursion();
}
if (this.RightChild != null)
{
this.RightChild.Preorder_Recursion();
}
}
public void Preorder()
{
Stack<TwoXTree> stack = new Stack<TwoXTree>();
Stack<bool> stack2 = new Stack<bool>();
TwoXTree node = this;
bool flag; // used to check if already visit both the left child and the right child of current node
do
{
while (node != null)
{
Visit(node);
stack.Push(node);
stack2.Push(false);
node = node.LeftChild;
}
node = stack.Pop();
flag = stack2.Pop();
if (flag)
{
node = null;
}
else
{
stack.Push(node);
stack2.Push(true);
node = node.RightChild;
}
} while (node != null || stack.Count > 0);
}
#endregion
#region Inorder
public void Inorder_Recursion()
{
if (this.LeftChild != null)
{
this.LeftChild.Inorder_Recursion();
}
Visit(this);
if (this.RightChild != null)
{
this.RightChild.Inorder_Recursion();
}
}
public void Inorder()
{
Stack<TwoXTree> stack = new Stack<TwoXTree>();
Stack<bool> stack2 = new Stack<bool>();
TwoXTree node = this;
bool flag;
do
{
while (node != null)
{
stack.Push(node);
stack2.Push(false);
node = node.LeftChild;
}
node = stack.Pop();
flag = stack2.Pop();
if (flag)
{
node = null;
}
else
{
Visit(node);
stack.Push(node);
stack2.Push(true);
node = node.RightChild;
}
} while (node != null || stack.Count > 0);
}
#endregion
#region Posorder
public void Posorder_Recursion()
{
if (this.LeftChild != null)
{
this.LeftChild.Posorder_Recursion();
}
if (this.RightChild != null)
{
this.RightChild.Posorder_Recursion();
}
Visit(this);
}
public void Posorder()
{
Stack<TwoXTree> stack = new Stack<TwoXTree>();
Stack<bool> stack2 = new Stack<bool>();
TwoXTree node = this;
bool flag;
do
{
while (node != null)
{
stack.Push(node);
stack2.Push(false);
node = node.LeftChild;
}
node = stack.Pop();
flag = stack2.Pop();
if (flag)
{
Visit(node);
node = null;
}
else
{
stack.Push(node);
stack2.Push(true);
node = node.RightChild;
}
} while (node != null || stack.Count > 0);
}
#endregion
#region Layer Order
public void LayerOrder()
{
Queue<TwoXTree> queue = new Queue<TwoXTree>();
queue.Enqueue(this);
TwoXTree node;
while (queue.Count > 0)
{
node = queue.Dequeue();
Visit(node);
if (node.LeftChild != null)
queue.Enqueue(node.LeftChild);
if (node.RightChild != null)
queue.Enqueue(node.RightChild);
}
}
#endregion
4. 统计总节点数：
代码
#region Get total count
/// <summary>
/// Get total count by recursion
/// </summary>
/// <returns></returns>
public int GetTotalCount_Recursion()
{
int totalCount = 1;
if (this.LeftChild != null)
totalCount += this.LeftChild.GetTotalCount_Recursion();
if (this.RightChild != null)
totalCount += this.RightChild.GetTotalCount_Recursion();
return totalCount;
}
/// <summary>
/// Get total count
/// </summary>
/// <returns></returns>
public int GetTotalCount()
{
Queue<TwoXTree> queue = new Queue<TwoXTree>();
TwoXTree node = this;
int totalCount = 0;
while (node != null)
{
++totalCount;
if (node.LeftChild != null)
queue.Enqueue(node.LeftChild);
if (node.RightChild != null)
queue.Enqueue(node.RightChild);
if (queue.Count > 0)
{
node = queue.Dequeue();
}
else
{
node = null;
}
}
return totalCount;
}
#endregion
/// <summary>
/// Get total count by recursion
/// </summary>
/// <returns></returns>
public int GetTotalCount_Recursion()
{
int totalCount = 1;
if (this.LeftChild != null)
totalCount += this.LeftChild.GetTotalCount_Recursion();
if (this.RightChild != null)
totalCount += this.RightChild.GetTotalCount_Recursion();
return totalCount;
}
/// <summary>
/// Get total count
/// </summary>
/// <returns></returns>
public int GetTotalCount()
{
Queue<TwoXTree> queue = new Queue<TwoXTree>();
TwoXTree node = this;
int totalCount = 0;
while (node != null)
{
++totalCount;
if (node.LeftChild != null)
queue.Enqueue(node.LeftChild);
if (node.RightChild != null)
queue.Enqueue(node.RightChild);
if (queue.Count > 0)
{
node = queue.Dequeue();
}
else
{
node = null;
}
}
return totalCount;
}
#endregion
5. 树的最大层数：
代码
#region Get max length
public int GetMaxLength_Recursion()
{
int left = 0, right = 0;
if (this.LeftChild != null)
left = this.LeftChild.GetMaxLength_Recursion();
if (this.RightChild != null)
right = this.RightChild.GetMaxLength_Recursion();
return left > right ? left + 1 : right + 1;
}
public int GetMaxLength()
{
Queue<TwoXTree> treeQueue = new Queue<TwoXTree>();
Queue<int> lengthQueue = new Queue<int>();
TwoXTree node = this;
int length = 0;
treeQueue.Enqueue(node);
lengthQueue.Enqueue(1);
while (treeQueue.Count > 0)
{
node = treeQueue.Dequeue();
length = lengthQueue.Dequeue();
if (node.LeftChild != null)
{
treeQueue.Enqueue(node.LeftChild);
lengthQueue.Enqueue(length + 1);
}
if (node.RightChild != null)
{
treeQueue.Enqueue(node.RightChild);
lengthQueue.Enqueue(length + 1);
}
}
return length;
}
#endregion
public int GetMaxLength_Recursion()
{
int left = 0, right = 0;
if (this.LeftChild != null)
left = this.LeftChild.GetMaxLength_Recursion();
if (this.RightChild != null)
right = this.RightChild.GetMaxLength_Recursion();
return left > right ? left + 1 : right + 1;
}
public int GetMaxLength()
{
Queue<TwoXTree> treeQueue = new Queue<TwoXTree>();
Queue<int> lengthQueue = new Queue<int>();
TwoXTree node = this;
int length = 0;
treeQueue.Enqueue(node);
lengthQueue.Enqueue(1);
while (treeQueue.Count > 0)
{
node = treeQueue.Dequeue();
length = lengthQueue.Dequeue();
if (node.LeftChild != null)
{
treeQueue.Enqueue(node.LeftChild);
lengthQueue.Enqueue(length + 1);
}
if (node.RightChild != null)
{
treeQueue.Enqueue(node.RightChild);
lengthQueue.Enqueue(length + 1);
}
}
return length;
}
#endregion
6. 测试：
代码
string tree = "A(B(C(E(H,),F),D(,I)),J(K,L(M(,N),)))";
TwoXTree twoXTree = TwoXTree.CreateTwoXTree(tree);
int totalCount = twoXTree.GetTotalCount();
int totalCountRecursion = twoXTree.GetTotalCount_Recursion();
int maxLength = twoXTree.GetMaxLength();
int maxLengthRecursion = twoXTree.GetMaxLength_Recursion();
Console.WriteLine("Preorder: ");
twoXTree.Preorder_Recursion();
Console.WriteLine();
twoXTree.Preorder();
Console.WriteLine();
Console.WriteLine("Inorder: ");
twoXTree.Inorder_Recursion();
Console.WriteLine();
twoXTree.Inorder();
Console.WriteLine();
Console.WriteLine("Posorder: ");
twoXTree.Posorder_Recursion();
Console.WriteLine();
twoXTree.Posorder();
Console.WriteLine();
Console.WriteLine("Layer Order: ");
twoXTree.LayerOrder();
Console.WriteLine();
TwoXTree twoXTree = TwoXTree.CreateTwoXTree(tree);
int totalCount = twoXTree.GetTotalCount();
int totalCountRecursion = twoXTree.GetTotalCount_Recursion();
int maxLength = twoXTree.GetMaxLength();
int maxLengthRecursion = twoXTree.GetMaxLength_Recursion();
Console.WriteLine("Preorder: ");
twoXTree.Preorder_Recursion();
Console.WriteLine();
twoXTree.Preorder();
Console.WriteLine();
Console.WriteLine("Inorder: ");
twoXTree.Inorder_Recursion();
Console.WriteLine();
twoXTree.Inorder();
Console.WriteLine();
Console.WriteLine("Posorder: ");
twoXTree.Posorder_Recursion();
Console.WriteLine();
twoXTree.Posorder();
Console.WriteLine();
Console.WriteLine("Layer Order: ");
twoXTree.LayerOrder();
Console.WriteLine();
