初学Python常见错误 忘记写冒号 误用= 错误 缩紧 变量没有定义 中英文输入法导致的错误 不同数据类型的拼接 索引位置问题 使用字典中不存在的键 忘了括号 漏传参数 缺失依赖库 使用了python中对关键词 编码问题 1. 忘记写冒号 在 if.elif.else.for.while.def语句后面忘记添加 : age = 42 if age == 42 print('Hello!') File "<ipython-input-19-4303141d6f97>", l…

题目连接 http://poj.org/problem?id=1679 The Unique MST Description Given a connected undirected graph, tell if its minimum spanning tree is unique. Definition 1 (Spanning Tree): Consider a connected, undirected graph G = (V, E). A spanning tree of G is a…

Description Given a connected undirected graph, tell if its minimum spanning tree is unique.  Definition 1 (Spanning Tree): Consider a connected, undirected graph G = (V, E). A spanning tree of G is a subgraph of G, say T = (V', E'), with the followi…

目录 唯一性索引unique影响: unique与primary key的区别: 存在唯一键冲突时,避免策略: insert ignore: replace into: insert on duplicate key update: 结论: 参考: 唯一性索引unique影响: 唯一性索引表创建: DROP TABLE IF EXISTS `sc`; CREATE TABLE `sc` ( `id` int(11) NOT NULL AUTO_INCREMENT, `name` varchar(…

提到二叉查找树,就得想到二叉查找树的递归定义, 左子树的节点值都小于根节点,右子树的节点值都大于根节点. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 给定一个n,问有多少个不同的二叉查找树,使得每个节点的值为 1...n? 例如, 给定n=3,你的程序应该返回所有的这5个不同的二叉排序树的个数. 1 3 3 2 1 \ / / / \ \ 3 2 1 1 3 2 / / \…

创建了一个Django项目,且包含一个admin的app,但是在启动Django的是时候抛出了以下异常: Unhandled exception in thread started by <function check_errors.<locals>.wrapper at 0x00000180A3C34400> Traceback (most recent call last): File "C:\Python37\lib\site-packages\django\uti…

Consider the string s to be the infinite wraparound string of "abcdefghijklmnopqrstuvwxyz", so s will look like this: "...zabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcd....". Now we have another string p. Your job is to find…

A string such as "word" contains the following abbreviations: ["word", "1ord", "w1rd", "wo1d", "wor1", "2rd", "w2d", "wo2", "1o1d", "1or1", "…

Given a non-negative integer n, count all numbers with unique digits, x, where 0 ≤ x < 10n. Example: Given n = 2, return 91. (The answer should be the total numbers in the range of 0 ≤ x < 100, excluding [11,22,33,44,55,66,77,88,99]) Hint: A direct…

An abbreviation of a word follows the form <first letter><number><last letter>. Below are some examples of word abbreviations: a) it --> it (no abbreviation) 1 b) d|o|g --> d1g 1 1 1 1---5----0----5--8 c) i|nternationalizatio|n --&…