Add files via upload

Author: assassint2017

Binary Tree Postorder Traversal/Binary_Tree_Postorder_Traversal.cpp

@@ -0,0 +1,54 @@
+// 树的三种序的遍历 后序的非递归形式是最难的
+// 0ms 100%
+
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+ * };
+ */
+#include<vector>
+#include<stack>
+using namespace std;
+
+class Solution {
+public:
+    vector<int> postorderTraversal(TreeNode* root) {
+        vector<int> values;
+        stack<TreeNode*> treeStack;
+        TreeNode *preNode = 0;
+        
+        if (!root)
+            return values;
+        
+        while(root || !treeStack.empty())
+        {
+            while (root)
+            {
+                treeStack.push(root);
+                root = root->left;
+            }
+            if (!treeStack.empty())
+            {
+                root = treeStack.top();
+                treeStack.pop();
+
+                if (root->right == 0 || root->right == preNode)
+                {
+                    values.push_back(root->val);
+                    preNode = root;
+                    root = 0;
+                }
+                else
+                {
+                    treeStack.push(root);
+                    root = root->right;
+                }
+            }
+        }
+        return values;
+    }
+};

Binary Tree Postorder Traversal/Binary_Tree_Postorder_Traversal.py

@@ -0,0 +1,36 @@
+# 56ms 80.13%
+
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution:
+    def postorderTraversal(self, root):
+        """
+        :type root: TreeNode
+        :rtype: List[int]
+        """
+        values = []
+        stack = []
+        preNode = 0
+
+        if (root is None):
+            return values
+        
+        while root or len(stack) > 0:
+            while root:
+                stack.append(root)
+                root = root.left
+            if len(stack) > 0:
+                root = stack.pop()
+                if root.right is None or root.right == preNode:
+                    values.append(root.val)
+                    preNode = root;
+                    root = None
+                else:
+                    stack.append(root)
+                    root = root.right
+        return values