题目描述：

LeetCode 515. Find Largest Element in Each Row

You need to find the largest value in each row of a binary tree.

Example:

Input: 

          1
         / \
        3   2
       / \   \  
      5   3   9 

Output: [1, 3, 9]

题目大意：

给定二叉树，返回其每一行的最大元素。

解题思路：

二叉树的层次遍历 ...

题目描述：

LeetCode 513. Find Left Most Element

Given a binary tree, find the leftmost value in the last row of the tree.

Example 1:

Input:

    2
   / \
  1   3

Output:
1

Example 2:

Input:

        1
       / \
      2   3
     /   / \
    4   5   6
       /
      7 ...

题目描述：

LeetCode 504. Base 7

Given an integer, return its base 7 string representation.

Example 1:

Input: 100
Output: "202"

Example 2:

Input: -7
Output: "-10"

Note: The input will be in range of [-1e7, 1e7].

题目大意：

给定一个整数，返回其7进制的字符串 ...

LeetCode Weekly Contest 18b是LeetCode举办的第二十三场正式周赛，共4道题目，比赛时长1.5小时。

比赛链接：https://leetcode.com/contest/leetcode-weekly-contest-18b/

题解列表：

LeetCode 496. Next Greater Element I

LeetCode 506. Relative Ranks

LeetCode 503. Next Greater Element II

LeetCode 498. Diagonal Traverse

题目描述：

LeetCode 498. Diagonal Traverse

Given a matrix of M x N elements (M rows, N columns), return all elements of the matrix in diagonal order.

Example 1:

Input:
[
 [ 1, 2, 3 ],
 [ 4, 5, 6 ],
 [ 7, 8, 9 ]
]
Output:  [1 ...