Binary Tree Zigzag Level Order Traversal
Given the root of a binary tree, return the zigzag level order traversal of its nodes' values. (i.e., from left to right, then right to left for the next level and alternate between). Example 1: Input: root = [3,9,20,null,null,15,7] Output: [[3],[20,9],[15,7]] Example 2: Input: root = [1] Output: [[1]] Example 3: Input: root = [] Output: []
View Solution →Convert Sorted Array to Binary Search Tree
Given an integer array nums where the elements are sorted in ascending order, convert it to a height-balanced binary search tree. Example 1: Input: nums = [-10,-3,0,5,9] Output: [0,-3,9,-10,null,5] Explanation: [0,-10,5,null,-3,null,9] is also accepted: Example 2: Input: nums = [1,3] Output: [3,1] Explanation: [1,null,3] and [3,1] are both height-balanced BSTs. Constraints: 1 <= nums.length <= 104 -104 <= nums[i] <= 104 nums is sorted in a strictly increas
View Solution →Convert Sorted List to Binary Search Tree
Given the head of a singly linked list where elements are sorted in ascending order, convert it to a height-balanced binary search tree. Example 1: Input: head = [-10,-3,0,5,9] Output: [0,-3,9,-10,null,5] Explanation: One possible answer is [0,-3,9,-10,null,5], which represents the shown height balanced BST. Example 2: Input: head = [] Output: [] Constraints: The number of nodes in head is in the range [0, 2 * 104]. -105 <= Node.val <= 105
View Solution →Flatten Binary Tree to Linked List
Given the root of a binary tree, flatten the tree into a "linked list": The "linked list" should use the same TreeNode class where the right child pointer points to the next node in the list and the left child pointer is always null. The "linked list" should be in the same order as a pre-order traversal of the binary tree. Example 1: Input: root = [1,2,5,3,4,null,6] Output: [1,null,2,null,3,null,4,null,5,null,6] Example 2: Input: root = [] Output: [] Example 3: Input: ro
View Solution →Distinct Subsequences
Given two strings s and t, return the number of distinct subsequences of s which equals t. The test cases are generated so that the answer fits on a 32-bit signed integer. Example 1: Input: s = "rabbbit", t = "rabbit" Output: 3 Explanation: As shown below, there are 3 ways you can generate "rabbit" from s. rabbbit rabbbit rabbbit Example 2: Input: s = "babgbag", t = "bag" Output: 5 Explanation: As shown below, there are 5 ways you can generate "bag" from s. babgbag b
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