261. Graph Valid Tree
261. Graph Valid Tree
題目給定一個數字 n 和一個陣列，n 代表的是一個圖中，所用有的節點數量，
Tree
124. Binary Tree Maximum Path Sum
124. Binary Tree Maximum Path Sum
這一題是後序遍歷的經典題目，後序遍歷的精神就是先將子樹的問題全部解決，再開始處理跟節點的問題，這一題要怎麼想到的確是屬於困難的題型。
106. Construct Binary Tree from Inorder and Postorder Traversal
106. Construct Binary Tree from Inorder and Postorder Traversal
postorder
559. Maximum Depth of N-ary Tree
559. Maximum Depth of N-ary Tree
"""
# Definition
222. Count Complete Tree Nodes
222. Count Complete Tree Nodes
線性搜索
# Definition for a binary
286. Walls and Gates
286. Walls and Gates
題目給定一個矩陣，矩陣內有標記了牆與門，剩餘的點被標註成一個無限大的數值，意義為可以行走的點，要求把這些矩陣中除了門與牆以外的點，以該點到達附近最近的門的距離為何？
1373. Maximum Sum BST in Binary Tree
1371. Maximum Sum BST in Binary Tree
# Definition for a
94. Binary Tree Inorder Traversal
94. Binary Tree Inorder Traversal
# Definition for a binary tree
297. Serialize and Deserialize Binary Tree
297. Serialize and Deserialize Binary Tree
這一題可以透過 536. Construct Binary
144. Binary Tree Preorder Traversal
144. Binary Tree Preorder Traversal
# Definition for a binary tree