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문제 링크: https://leetcode.com/problems/find-original-array-from-doubled-array/ 문제 An integer array original is transformed into a doubled array changed by appending twice the value of every element in original, and then randomly shuffling the resulting array. Given an array changed, return original if changed is a doubled array. If changed is not a doubled array, return an empty array. The element..

문제 링크: https://leetcode.com/problems/pseudo-palindromic-paths-in-a-binary-tree/ 문제 Given a binary tree where node values are digits from 1 to 9. A path in the binary tree is said to be pseudo-palindromic if at least one permutation of the node values in the path is a palindrome. Return the number of pseudo-palindromic paths going from the root node to leaf nodes. 조건 The number of nodes in the tr..

문제 링크: https://leetcode.com/problems/binary-tree-inorder-traversal/ 문제 Given the root of a binary tree, return the inorder traversal of its nodes' values. 조건 The number of nodes in the tree is in the range [0, 100]. -100

문제 링크: https://leetcode.com/problems/construct-string-from-binary-tree/ 문제 Given the root of a binary tree, construct a string consisting of parenthesis and integers from a binary tree with the preorder traversal way, and return it. Omit all the empty parenthesis pairs that do not affect the one-to-one mapping relationship between the string and the original binary tree. 조건 The number of nodes i..

문제 링크: https://leetcode.com/problems/binary-tree-pruning/ 문제 Given the root of a binary tree, return the same tree where every subtree (of the given tree) not containing a 1 has been removed. A subtree of a node node is node plus every node that is a descendant of node. 조건 The number of nodes in the tree is in the range [1, 200]. Node.val is either 0 or 1. 내 풀이 Tree 구조 관련 문제는 recursive하게 짠다. dfs..

문제 링크: https://leetcode.com/problems/n-ary-tree-level-order-traversal/ 문제 Given an n-ary tree, return the level order traversal of its nodes' values. Nary-Tree input serialization is represented in their level order traversal, each group of children is separated by the null value (See examples). 조건 The height of the n-ary tree is less than or equal to 1000 The total number of nodes is between [0..

문제 링크: https://leetcode.com/problems/average-of-levels-in-binary-tree/ 문제 Given the root of a binary tree, return the average value of the nodes on each level in the form of an array. Answers within $10^{-5}$ of the actual answer will be accepted. 조건 The number of nodes in the tree is in the range [1, $10^4$]. $-2^{31}$

문제 링크: https://leetcode.com/problems/count-good-nodes-in-binary-tree/ 문제 Given a binary tree root, a node X in the tree is named good if in the path from root to X there are no nodes with a value greater than X. Return the number of good nodes in the binary tree. 조건 The number of nodes in the binary tree is in the range [1, 10^5]. Each node's value is between [-10^4, 10^4]. 내 풀이 Tree 구조는 항상 recu..