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Articles on Trending Technologies
Technical articles with clear explanations and examples
Binary Indexed Tree or Fenwick Tree in C++?
In case of comparing with a flat array of numbers, the Fenwick tree results a much better balance between two operations: element update and prefix sum computation. In case of a flat array of m numbers, we can either store the elements, or the prefix sums. In case of first instance, calculating prefix sums needs linear time; in case of second instance, modifying or updating the array elements needs linear time (in both instances, the other operation can be accomplished in constant time). Fenwick trees permit both operations to be accomplished in O(log m) time. This is obtained by representing ...
Read MoreConverting one string to other using append and delete last operations in C++
In this tutorial, we will be discussing a program to convert one string to other using append and delete last operations.For this we will be provided with two strings. Our task is to calculate whether the first string can be converted into the second one by performing k operations of append and delete last element.Example#include using namespace std; //checking if conversion between strings is possible bool if_convert(string str1, string str2, int k){ if ((str1.length() + str2.length()) < k) return true; //finding common length of both string int commonLength = 0; for (int i = ...
Read MoreElse and Switch Statements with initializers in C++17
In many cases, we need to verify the value of something returned by a function and perform conditional operations based on this value. So our code is given below −// Some method or function return_type foo(Params) // Call function with Params and // store return in var1 auto var1 = foo(Params); if (var1 == /* some value */) { //Perform Something } else { //Perform Something else }Just follow the general format in all conditional if-else blocks. Firstly there is exist an optional initial statement which sets up the variable, followed by the if-else block. So the general ...
Read More2-Satisfiability(2-SAT) Problem in C/C++?
Let f = (x1 ∨ y1) ∧ (x2 ∨ y2) ∧ ... ∧ (xn ∨ yn).Problem: Is f satisfiable?xi ∨ yi and and are all equivalent. So we are converting each of (xi ∨ yi) s into those two statements.Now assume a graph with 2n vertices. In case of each of (xi∨yi) s two directed edges are addedFrom ¬xi to yiFrom ¬yi to xif is not treated as satisfiable if both ¬xi and xi are in the same SCC (Strongly Connected Component)Assume that f is treated as satisfiable. Now we want to provide values to each variable in order to satisfy ...
Read MoreWhich punctuation character can be used as the delimiter between MySQL date parts?
In this matter, MySQL permits us to use a relaxed format to date. We can use any punctuation character between date parts as a delimiter. Some examples are as follows −mysql> Select date ('2016/10/20'); +---------------------+ | date ('2016/10/20') | +---------------------+ | 2016-10-20 | +---------------------+ 1 row in set (0.00 sec) mysql> Select date('2016^10^20'); +--------------------+ | date('2016^10^20') | +--------------------+ | 2016-10-20 | +--------------------+ 1 row in set (0.00 sec) mysql> Select date ('2016@10@20'); +---------------------+ | date ('2016@10@20') | +---------------------+ | 2016-10-20 | +---------------------+ 1 row in set (0.00 sec) mysql> Select date ('2016+10+20'); +---------------------+ | date ('2016+10+20') | +---------------------+ | 2016-10-20 | +---------------------+ 1 row in set (0.00 sec)
Read MoreHow can I use any character, at the place of space, in MySQL TIMESTAMP to distinguish between date and time parts?
We can use the only character ‘T’ (in Capital form only) at the place of space between date and time part. It can be elucidated with the help of the following example −mysql> Select TIMESTAMP('2017-10-20T06:10:36'); +----------------------------------+ | TIMESTAMP('2017-10-20T06:10:36') | +----------------------------------+ | 2017-10-20 06:10:36 | +----------------------------------+ 1 row in set (0.00 sec)
Read MoreWhat MySQL returns on using any other character than 'T' or 'Space' between date and time parts?
In that case, MySQL will return all zeros at the place of time along with correct date part. An example is as follows in which we used character ‘W’ at the place of ‘T’ or ‘Space’ between date and time part −mysql> Select TIMESTAMP('2017-10-20W06:10:36'); +----------------------------------+ | TIMESTAMP('2017-10-20W06:10:36') | +----------------------------------+ | 2017-10-20 00:00:00 | +----------------------------------+ 1 row in set, 1 warning (0.00 sec)
Read MoreHow can MySQL interpret the number and string, having no delimiter, as a date?
If a string or number, even without any delimiter, in the format of YYYYMMDDHHMMSS or YYMMDDHHMMSS is making sense as the date is provided then MySQL interpret that string as a valid date.Examples are given for valid as well as invalid dates −mysql> Select Timestamp(20171022040536); +---------------------------+ | Timestamp(20171022040536) | +---------------------------+ | 2017-10-22 04:05:36 | +---------------------------+ 1 row in set (0.00 sec) mysql> Select Timestamp('20171022040536'); +-----------------------------+ | Timestamp('20171022040536') | +-----------------------------+ | 2017-10-22 04:05:36 | +-----------------------------+ 1 row in set (0.00 sec) mysql> Select Timestamp('171022040536'); +---------------------------+ | Timestamp('171022040536') | +---------------------------+ | 2017-10-22 04:05:36 ...
Read MoreHow many digits should be there in string or number so that it can be specified as a date value by MySQL?
While considering the year as 4-digit value, minimum of 8 digits in a string or number is required for MySQL to specify it as a date value. In this case, if we also want to store microseconds then the value can be up to a maximum of 20 digits.mysql> Select TIMESTAMP('20171022040536.100000'); +-----------------------------------+ | TIMESTAMP('20171022040536100000') | +-----------------------------------+ | 2017-10-22 04:05:36.100000 | +-----------------------------------+ 1 row in set, 1 warning (0.00 sec)The query above is taking 20 digits string for TIMESTAMP value. Last 6 digits are for microseconds.mysql> Select TIMESTAMP(20171022); +---------------------+ | TIMESTAMP(20171022) | +---------------------+ | 2017-10-22 00:00:00 | +---------------------+ ...
Read MoreHow can we use WHERE condition when creating a table with CTAS (Create Table as Selected) script?
As we know that we can copy the data and structure from an existing table by CTAS script. Use of WHERE clause is demonstrated in the example belowmysql> Create table EMP_BACKUP2 AS SELECT * from EMPLOYEE WHERE id = 300 AND Name = 'Mohan'; Query OK, 1 row affected (0.14 sec) Records: 1 Duplicates: 0 Warnings: 0 mysql> Select * from EMP_BACKUP2; +------+-------+ | Id | Name | +------+-------+ | 300 | Mohan | +------+-------+ 1 row in set (0.00 sec)In the example above, we have created a table named EMP_BACKUP1 from table ‘Employee’ with some conditions. MySQL creates the table with only one row based on those conditions.
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