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Author: coderpheonix

102. Binary Tree Level Order Traversal.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>> levelOrder(TreeNode* root) {
+
+       vector<vector<int>> result;
+       if(!root) return result; // return nothing if the root is nullptr
+
+       queue<TreeNode*>q;
+       q.push(root);
+
+       // continue the process untill there is no node
+       while(!q.empty())
+       {
+        int size = q.size();
+        vector<int> level;
+
+         // run the loop to process each node
+        for (int i=0; i<size;i++)
+        {
+            /// Get the next node from the front of the queue.
+            TreeNode* node=q.front();
+            q.pop();
+            level.push_back(node->val);
+             // if the curent node has a left child
+            if(node->left) q.push(node->left);
+
+            if(node-> right) q.push(node-> right);
+        }
+        result.push_back(level);
+       }
+
+       return result;
+    }
+};