# Algorithms Design Techniques

Algorithms are used to manipulate the data contained in data structures. When working with data structures, algorithms are used to perform operations on the stored data. A complex algorithm is often divided into smaller units called modules. This process of dividing an algorithm into modules is called modularization. The key advantages of modularization are as follows:

• It makes the complex algorithm simpler to design and implement

• Each module can be designed independently. While designing one module, the details of other modules can be ignored, thereby enhancing clarity in design which in turn simplifies implementation, debugging, testing, documenting, and maintenance of the overall algorithm.

## There are two main approaches to design an algorithm

### 2. Bottom-up approach

Algorithms Design Techniques-What are the different approaches to design an Algorithm

### 1. Top-down approach

A top-down design approach starts by dividing the complex algorithm into one or more modules. These modules can further be decomposed into one or more sub-modules, and this process of decomposition is iterated until the desired level of module complexity is achieved. Top-down design method is a form of stepwise refinement where we begin with the topmost module and incrementally add modules that it calls.

Therefore, in a top-down approach, we start from an abstract design and then at each step. this design is refined into more concrete levels until a level is reached that requires no further refinement.

### 2. Bottom-up approach

A bottom-up approach is just the reverse of top-down approach. In the bottom-up design, we start with designing the most basic or concrete modules and then proceed towards designing higher level modules. The higher level modules are implemented by using the operations performed by lower level modules. Thus, in this approach sub-modules are grouped together to form a higher level module. All the higher level modules are clubbed together to form even higher level modules. This process is repeated until the design of the complete algorithm is obtained.

### Difference Between Top-down approach and Bottom-up approach

Top-down approachBottom-up approach
The top-down strategy should be followedBottom-up is a question that can be answered depending on the application at hand.
Top-down approach follows a stepwise refinement by decomposing the algorithm ins manageable modulesThe bottom-up approach on the other hand defines a module and then gre together several modules to form a new higher level module.
Top-down approach is highly appreciated for ease in documenting the modules, generation of test cases, implementation of code, and debugging. However, it is also criticized because the sub-modules are analysed in isolation without concentrating on their communication with other modules or on reusability of components and little attention is paid to data, thereby ignoring the concept of information hiding.Although the bottom-up approach allows information hiding as it first identifies what has y be encapsulated within a module and then provides an abstract interface to define the module boundaries as seen from the elements. But all this is difficult to be done in a strict bottom-up state Some top-down activities need to be performed for this.

TIME AND SPACE COMPLEXITY Of AN ALGORITHM

Data Structures & Algorithms | What Is Data Structures?

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