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
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 --&
Given n, how many structurally unique BST's (binary search trees) that store values 1...n? For example,Given n = 3, there are a total of 5 unique BST's. 1 3 3 2 1 \ / / / \ \ 3 2 1 1 3 2 / / \ \ 2 1 2 3 这道题实际上是Catalan Number卡塔兰数的一个例子,如果对卡塔兰数不熟悉的童鞋可能真
Given n, generate all structurally unique BST's (binary search trees) that store values 1...n. For example,Given n = 3, your program should return all 5 unique BST's shown below. 1 3 3 2 1 \ / / / \ \ 3 2 1 1 3 2 / / \ \ 2 1 2 3 confused what "{1,#,2
Follow up for "Unique Paths": Now consider if some obstacles are added to the grids. How many unique paths would there be? An obstacle and empty space is marked as 1 and 0 respectively in the grid. For example, There is one obstacle in the middl
A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below). The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (marked 'Finish' in t
Given n, generate all structurally unique BST's (binary search trees) that store values 1...n. For example, Given n = 3, your program should return all 5 unique BST's shown below. 1 3 3 2 1 \
487down vote Differences KEY or INDEX refers to a normal non-unique index. Non-distinct values for the index are allowed, so the index may contain rows with identical values in all columns of the index. These indexes don't enforce any restraints on
相信不少人遇到过ORA-02429: cannot drop index used for enforcement of unique /primary key 这个错误,对应的中文提示"ORA-02429: 无法删除用于强制唯一/主键的索引",其实从错误提示信息已经很明显了.下面还是用一个简单的例子述说一下该错误的来龙去脉. ORA-02429错误的原因是因为用户试图删除一个用于强制唯一/主键的索引,解决方法也很简单,删除对应的约束就会自动删除该索引. [oracle@DB-Serv
最近遇到一个关于发布订阅(Replication)的奇葩问题,特此记录一下这个案例.我们一SQL SERVER数据库服务器出现大量告警.告警信息如下所示: DESCRIPTION: Replication-Replication Distribution Subsystem: agent xxxxxx failed. Column names in each table must be unique. Column name 'xxxxx' in table 'dbo.xxxxxx' is sp
The Unique MST Time Limit: 1000MS Memory Limit: 10000K Total Submissions: 28673 Accepted: 10239 Description Given a connected undirected graph, tell if its minimum spanning tree is unique. Definition 1 (Spanning Tree): Consider a connected, undir
