1 . 二叉树的遍历
1020 Tree Traversals
1086 Tree Traversals Again
1102 Invert a Binary Tree

2 . 树的遍历
1090 Highest Price in Supply Chain
1106 Lowest Price in Supply Chain
1079 Total Sales of Supply Chain
1094 The Largest Generation
1004 Counting Leaves

3 . 二叉查找树
1043 Is It a Binary Search Tree
1064 Complete Binary Search Tree
1099 Build A Binary Search Tree

4 . 平衡二叉树
1066 Root of AVL Tree

5 . 并查集
1107 Social Clusters

待补充，持续更新中