# 归档 2017年9月3日

## LeetCode Weekly Contest 48解题报告 作者是 在线疯狂 发布于 2017年9月3日 在 LeetCode.

LeetCode Weekly Contest 48是LeetCode举办的第五十三场正式周赛，共4道题目，比赛时长1.5小时。

LeetCode 671. Second Minimum Node In a Binary Tree

LeetCode 669. Trim a Binary Search Tree

LeetCode 670. Maximum Swap

LeetCode 672. Bulb Switcher II

## 题目描述：

LeetCode 672. Bulb Switcher II

There is a room with `n` lights which are turned on initially and 4 buttons on the wall. After performing exactly `m` unknown operations towards buttons, you need to return how many different kinds ...

## 题目描述：

LeetCode 670. Maximum Swap

Given a non-negative integer, you could swap two digits at most once to get the maximum valued number. Return the maximum valued number you could get.

Example 1:

```Input: 2736
Output: 7236
Explanation: Swap the ...```

## 题目描述：

LeetCode 669. Trim a Binary Search Tree

Given a binary search tree and the lowest and highest boundaries as `L` and `R`, trim the tree so that all its elements lies in `[L, R]` (R >= L). You might ...

## 题目描述：

LeetCode 671. Second Minimum Node In a Binary Tree

Given a non-empty special binary tree consisting of nodes with the non-negative value, where each node in this tree has exactly `two` or `zero` sub-node. If the node has two ...