Computer Science 112 Spring 2014

Gregory M. Kapfhammer

Introduction to Computer Science II

Algorithms

Correctness

Performance

How fast is an algorithm?

Try some examples!

for loops

Constant

Linear

Quadratic

Cubic

git pull

CLASSPATH

Compile

Run!

Results?

Conclusions?

Algorithm

Function

Draw a Graph

Slow growing

Fast growing

Function Exploration

Fastest Growth?

Slowest Growth?

Conclusions?

Implications?

Take a step back

Limitations of empirical studies

Characterize programs as functions of input size

Hands-on Example

Largest Integer?

Computing Sums

Correct?

Incorrect?

Conduct an Experiment

Efficient?

Inefficient?

Why?

Pseudo code

When n gets big

Revisit computing sums

Best, Worst, Average

Worst-Case Graph

f(n) is O(g(n))

f(n) is O(g(n))

f(n) is O(g(n))

f(n) is O(g(n))