二叉樹前序、中序、後序遍歷遞歸、非遞歸

class NodeClass: def __init__(self, element): self.element = element self.left = None self.right = None returnPreList = [] def pre_digui(root): # 前序遍歷 遞歸 if root: returnPreList.append(root.element) pre_digui(root.left) pre_digui(root.right) def pre_duizhan(root): # 前序 堆棧 returnList = [] nodeList = [] node = root while nodeList or node: while node: nodeList.append(node) returnList.append(node.element) node = node.left node = nodeList.pop() node = node.right print(returnList) returnMidList = [] def mid_digui(root): # 中序遞歸 if root: mid_digui(root.left) returnMidList.append(root.element) mid_digui(root.right) def mid_duizhan(root): # 中序堆棧 returnList = [] nodeList = [] node = root while nodeList or node: while node: nodeList.append(node) node = node.left node = nodeList.pop() returnList.append(node.element) node = node.right print(returnList) returnPostList = [] def post_digui(root): # 後序遞歸 if root: post_digui(root.left) post_digui(root.right) returnPostList.append(root.element) def post_duizhan(root): # 後序堆棧 returnList = [] tempList = [root] while tempList: temp = tempList.pop() if type(temp) is NodeClass: tempList.append(temp.element) if temp.right: tempList.append(temp.right) if temp.left: tempList.append(temp.left) else: returnList.append(temp) print(returnList) def post_duizhan2(root): # 後序堆棧方法2 returnList = [] nodeList1 = [root] nodeList2 = [] while nodeList1: node = nodeList1.pop() nodeList2.append(node) if node.left: nodeList1.append(node.left) if node.right: nodeList1.append(node.right) while nodeList2: returnList.append(nodeList2.pop().element) print(returnList) root = NodeClass(0) root.left = NodeClass(1) root.right = NodeClass(2) root.left.left = NodeClass(3) root.left.right = NodeClass(4) root.right.left = NodeClass(5) root.right.right = NodeClass(6) # pre_digui(root) # print(returnPreList) # pre_duizhan(root) # mid_digui(root) # print(returnMidList) # mid_duizhan(root) post_digui(root) print(returnPostList) post_duizhan(root) post_duizhan2(root)