Lecture #5

An Introduction to Programming: Coding Decision Trees

If Statements
if (logical expression) { "true" actions
}
If - Else Statements
if (logical expression) { "true" actions } else { "false" actions
}
Logical Expression
- Simplest form if some kind of comparison
  - ==, !=
Assignment Statement

variable = expression;
- Note equal sign (=); only one
Method Invocation
- Arguments
Using Decisions to Solve Problems
- Must anticipate.
A Number Guessing Game
AboveBelow.java
AboveBelow.html
How Many Guesses Should it Take?
- For range 1-1,000,000?
Binary Search
- Telephone book or dictionary
Decision Trees
- Generally useful
  - Medical Diagnosis

Car Diagnosis Problem: Decision Tree

Can't get car's engine to run; what is the problem?
was car just running and quit now?	yes	is gas gauge on empty?	yes	get gas
			no	call tow truck
	no	does engine crank?	yes	check gas
			no	check battery