589. N 叉树的前序遍历
Easy | Stack, Tree, Depth-First Search
Easy
590. N 叉树的后序遍历
Easy | Stack, Tree, Depth-First Search
594. 最长和谐子序列
Easy | Array, Hash Table, Sliding Window, Sorting, Counting
598. 范围求和 II
Easy | Array, Math
605. 种花问题
Easy | Array, Greedy
617. 合并二叉树
Easy | Tree, Depth-First Search, Breadth-First Search, Binary Tree
628. 三个数的最大乘积
Easy | Array, Math, Sorting
637. 二叉树的层平均值
Easy | Tree, Depth-First Search, Breadth-First Search, Binary Tree
643. 子数组最大平均数 I
Easy | Array, Sliding Window
645. 错误的集合
Easy | Array, Hash Table, Bit Manipulation, Sorting