1
CSCE 350:
Data Structures and Algorithms
Chin-Tser Huang
University of South Carolina
02/27/2009 2
Announcement
Reading assignment: Chapter 5.2
Homework 3 is returned today
High 4, Average 3.35
Homework 4 is assigned on February 25 and
is due on Wednesday, March 4 in class
Please download it from class website
Have your answers neatly typed
Explain your answer clearly and adequately by
showing the steps
02/27/2009 3
Variable-size-decrease
A size reduction pattern varies from one iteration of an
algorithm to another
Example: Euclid’s algorithm for computing the greatest
common divisor
gcd(
m
,
n
) = gcd(
n
,
m
mod
n
)
The arguments on the right-hand side are always
smaller than those on the left-hand side
But they are not smaller neither by a constant nor by a
constant factor
02/27/2009 4
Insertion Sort
This is a typical decrease-by-one technique
Assume
A
[0..
i-
1] has been sorted, how to
achieve the sorted
A
[0..
i
]?
Solution: insert the last element
A
[
i
] to the right
position
02/27/2009 5
Example
Sort 89 45 68 90 29 34 17
02/27/2009 6
Pseudocode of Insertion Sort
