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Author: kedebug

BinaryTreeZigzagLevelOrderTraversal/BinaryTreeZigzagLevelOrderTraversal.cpp

@@ -0,0 +1,50 @@
+/**
+ * Definition for binary tree
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
+ * };
+ */
+class Solution {
+public:
+    vector<vector<int>> zigzagLevelOrder(TreeNode *root) {
+        // Start typing your C/C++ solution below
+        // DO NOT write int main() function
+        
+        vector<vector<int>> result;
+        if (root == NULL) return result;
+        
+        stack<TreeNode*> stackNow;
+        stack<TreeNode*> stackNext;
+        vector<int> value;
+        bool left2right = true;
+        stackNow.push(root);
+        
+        while (!stackNow.empty()) {
+            TreeNode *node = stackNow.top();
+            stackNow.pop();
+            value.push_back(node->val);
+            if (left2right) {
+                if (node->left)
+                    stackNext.push(node->left);
+                if (node->right)
+                    stackNext.push(node->right);
+            }
+            else {
+                if (node->right)
+                    stackNext.push(node->right);
+                if (node->left)
+                    stackNext.push(node->left);
+            }
+            if (stackNow.empty()) {
+                result.push_back(value);
+                value.clear();
+                left2right = !left2right;
+                swap(stackNow, stackNext);
+            }
+        }
+        return move(result);
+    }
+};