Time: 10 ms (21.91%), Space: 12.2 MB (99.40%) - LeetHub

Author: ayushnagar123

107-binary-tree-level-order-traversal-ii/107-binary-tree-level-order-traversal-ii.cpp

@@ -0,0 +1,34 @@
+/**
+ * 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:
+    int height(TreeNode* root){
+        if(!root) {
+            return 0;
+        }
+        return max(height(root->left), height(root->right))+1;
+    }
+    
+    void levelOrderHelper(TreeNode* root, int level, vector<vector<int>> &ans) {
+        if(root== NULL) return;
+        ans[level].push_back(root->val);
+        levelOrderHelper(root->left, level-1, ans);
+        levelOrderHelper(root->right, level-1, ans);
+    }
+
+    vector<vector<int>> levelOrderBottom(TreeNode* root) {
+        int h = height(root);
+        vector<vector<int>> ans(h, vector<int> {});
+        levelOrderHelper(root, h-1, ans);
+        return ans;
+    }
+};