Computer Science Programming Basics in Ruby

1.3 Algorithms

Algorithms are step-by-step methods of solving problems. The process of reading in names previously described is an example of an algorithm, though a very simple one. Some are extremely complicated, and many vary their execution depending on input. Often algorithms take input and generate output, but not always. However, all algorithms have something in common: they all do something.

Gem of Wisdom

Algorithms are the core of computer science. Correct and efficient algorithms guarantee that the computer works smart rather than only hard. Thus, think about the problem, come up with a good algorithm, and then determine how many steps the computer needs to complete the task.

Imagine a website like Google Maps, which has an algorithm to get directions from one point to another in either North America or Europe. It typically requires two inputs: a source and a destination. It also gives two outputs: the narrative directions to get from the source to the destination, and a map of the route.

The directions produced are also an algorithm; they accomplish the task of getting from the source to the destination. Imagine getting the directions to your friend’s house shown on the map in Figure 1-1.

1. Start going south on River Road.

2. Turn left (east) on Main Street.

3. Take a right (south) on Ruby Lane.

4. Turn left (east) toward Algorithm Circle.

5. Continue until you come to 345 Algorithm Circle (your friend’s house).

Figure 1-1. Directions “algorithm”

First notice that the directions ...