通过遍历的方式,分别建立 firstSearch() midSearch() lastSearch()来遍历二叉树收集前序,中序,后续, 然后在主函数里面append到一起 # class TreeNode: # def __init__(self, x): # self.val = x # self.left = None # self.right = None # # # @param root TreeNode类 the root of binary tree # @return int整型二维数组 # firstArr = [] midArr = [] lastArr = [] class Solution: def threeOrders(self , root ): # write code here res = [] #前序遍历 res.append(self.firstSearch(root)) res.append(self.midSearch(root)) res.append(self.lastSearch(root)) return res def firstSearch(self, root): if root: firstArr.append(root.val) self.firstSearch(root.left) self.firstSearch(root.right) return firstArr def midSearch(self, root): if root: self.midSearch(root.left) midArr.append(root.val) self.midSearch(root.right) return midArr def lastSearch(self, root): if root: self.lastSearch(root.left) self.lastSearch(root.right) lastArr.append(root.val) return lastArr