Definition and Properties of Trees

Mahesh Parahar
Published on 25-Aug-2019 06:15:32
Tree is a discrete structure that represents hierarchical relationships between individual elements or nodes. A tree in which a parent has no more than two children is called a binary tree.Tree and its PropertiesDefinition − A Tree is a connected acyclic undirected graph. There is a unique path between every ... Read More

Calendar in python

Pradeep Elance
Published on 25-Aug-2019 06:15:32
The calendar module in python has features to handle all the features related to calendar and dates. It is one of the very extensively used module which has many in-built functions to use dates in the python programs.Example Live Demoimport calendar print(calendar.calendar(2019))OutputRunning the above code gives us the following result −  ... Read More

Hamiltonian Graphs

Mahesh Parahar
Published on 25-Aug-2019 06:15:32
Hamiltonian graph - A connected graph G is called Hamiltonian graph if there is a cycle which includes every vertex of G and the cycle is called Hamiltonian cycle. Hamiltonian walk in graph G is a walk that passes through each vertex exactly once.Dirac's Theorem - If G is a ... Read More

Types of Graph

Mahesh Parahar
Published on 25-Aug-2019 06:15:32
There are various types of graphs depending upon the number of vertices, number of edges, interconnectivity, and their overall structure. We will discuss only a certain few important types of graphs in this chapter.Null GraphA graph having no edges is called a Null Graph.ExampleIn the above graph, there are three ... Read More

Return a specific MySQL string using regular expressions

AmitDiwan
Published on 25-Aug-2019 06:15:32
Let us first create a table −mysql> create table DemoTable649 (Value text); Query OK, 0 rows affected (0.68 sec)Insert some records in the table using insert command −mysql> insert into DemoTable649 values('1903'); Query OK, 1 row affected (0.08 sec) mysql> insert into DemoTable649 values('9321010'); Query OK, 1 row affected (0.14 ... Read More

Inverse of function of Set

Mahesh Parahar
Published on 25-Aug-2019 06:15:32
The inverse of a one-to-one corresponding function f: A → B, is the function g: B → A, holding the following property −f(x) = y ⇔ g(y) = xThe function f is called invertible if its inverse function g exists.ExampleA Function f : Z → Z, f(x)=x+5, is invertible since ... Read More

Depth First Search

Mahesh Parahar
Published on 25-Aug-2019 06:15:32
Graph traversal is the problem of visiting all the vertices of a graph in some systematic order. There are mainly two ways to traverse a graph.Breadth First SearchDepth First SearchDepth First Search (DFS) algorithm starts from a vertex v, then it traverses to its adjacent vertex (say x) that has ... Read More

Set current date and time to timestamp in MySQL

AmitDiwan
Published on 25-Aug-2019 06:15:32
Let us first create a table. One of the columns is set as TIMESTAMP −mysql> create table DemoTable648(    UserId int NOT NULL AUTO_INCREMENT, UserLoginTime TIMESTAMP NOT NULL    DEFAULT CURRENT_TIMESTAMP, PRIMARYKEY(UserId) ); Query OK, 0 rows affected (0.66 sec)Insert some records in the table using insert command. Here, we ... Read More

Homomorphism

Mahesh Parahar
Published on 25-Aug-2019 06:15:32
Two graphs G1 and G2 are said to be homomorphic, if each of these graphs can be obtained from the same graph 'G' by dividing some edges of G with more vertices. Take a look at the following example −Divide the edge 'rs' into two edges by adding one vertex.The ... Read More

How to display 3 random values from MySQL table?

AmitDiwan
Published on 25-Aug-2019 06:15:32
Use RAND() for random, whereas LIMIT 3 for the number of values i.e. 3 here −select yourColumnName from yourTableName order by rand() limit 3;Let us first create a table −mysql> create table DemoTable646 (    Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, FirstName varchar(100) ); Query OK, 0 rows affected ... Read More
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