Create main.cpp

Author: JawadSher

17 - Binary Tree Data Structure Problems/13 - Binary Tree Zigzag Level Order Traversal/main.cpp

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+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
+ * };
+ */
+class Solution {
+public:
+    vector<vector<int>> zigzagLevelOrder(TreeNode* root) {
+        vector<vector<int>> result;
+        if(root == NULL) return result;
+
+        queue<TreeNode*> q;
+        q.push(root);
+
+        bool LTR = true;
+
+        while(!q.empty()){
+            int size = q.size();
+            vector<int> ans(size);
+
+            for(int i = 0; i < size; i++){
+                TreeNode* frontNode = q.front();
+                q.pop();
+
+                int index = LTR ? i : size - i - 1;
+                ans[index] = frontNode -> val;
+
+                if(frontNode -> left) q.push(frontNode -> left);
+                if(frontNode -> right) q.push(frontNode -> right); 
+            }
+
+            LTR = !LTR;
+
+            result.push_back(vector<int>(ans.begin(), ans.end()));
+        }
+
+        return result;
+    }
+};