A graph is a data structure that consists of a set of nodes (vertices) connected by edges. A graph is cyclic if the graph comprises a path that starts from a node and ends at the same node. In this post, a simplified solution is provided to detect cycle and …
Build hierarchy tree reads employee data and build a corporation hierarchy tree from the list. HashMap plays important role to store the data when reading the input. The trick of this question is to find the root. You can get the root by finding the employee without the manager. Starting …
The modulo operation returns the remainder of one number divided by another. Modulo operator is a arithmetical operator, represented as %. One modulo operation example in math, 6 % 4 is 2. The modulo operation is also used in circular array. When an array index modulo (or mod) the array …
To find number of possible combinations of valid parentheses, we have to know Catalan number. Catalan numbers are a sequence of natural numbers that follow the formula showing below. The first few Catalan numbers for n = 0, 1, 2, 3, 4, 5 … Cn = 1, 1, 2, 5, …
Topological sort is a graph traversal in which node v is visited only after all its dependencies are visited. The graph has to be directed and has no cycles, i.e. directed acyclic graph (DAG). Once the graph is built, you can use the algorithms to find the order. The result …
A Euler path (Eulerian path) is a path in a graph that you visit each edge exactly once. You can visit the same vertex multiple times though. Dominoes is one example of finding Euler path problem. A domino is a game piece that has 2 numbers on it, one number …
A binary search tree is a type of ordered binary tree, where the left child has a value smaller than its parent, and the right child has a value greater than or equal to its parent. In a binary search tree, a node has two references, the left child and …
A circular queue is a queue in which all elements are connected to form a circular. A circular queue can be implemented with an array or a linked list. In the array implementation, the index of the rear element wraps around to the beginning of the array. In this post, …
A priority queue is a queue in which you insert an element at the back (enqueue) and remove an element from the front (dequeue). Meanwhile, a priority queue is a special queue, the element with the highest priority shall be dequeued first. You can implement a priority queue using an …
Google provides a powerful autocorrect for validating the keywords we type into the input text box. It checks against a dictionary. If it doesn’t find the keyword in the dictionary, it suggests a most likely replacement. To do this it associates with every word in the dictionary a frequency, the …
