Leetcode hot topic Hot 100, to be updated

1. I didn't look at the binary tree

Binary tree - Simple -6

94.  Middle order traversal of binary trees https://leetcode-cn.com/problems/binary-tree-inorder-traversal/

Simple recursive method ok

101.  Symmetric binary tree

Be careful ,BFS in , One is continue

104.  The maximum depth of a binary tree

Deque<TreeNode> deque = new LinkedList<>();

deque.add(root);

int size = deque.size(); // Note that this is not length

226.  Flip binary tree

again

543.  The diameter of a binary tree ​​​​​​

 again

617.  Merge binary tree

again, Well understood. , Do it again

2. Binary tree - secondary ,9 Avenue

96.  Different binary search trees

98.  Verify binary search tree

102.  Sequence traversal of binary tree

105.  Construction of binary trees from traversal sequences of preorder and middle order

 114.  The binary tree is expanded into a list

236.  The nearest common ancestor of a binary tree

337.  raid homes and plunder houses III

437.  The sum of the paths III

538.  Convert binary search tree to accumulation tree