1. Computer Science 111 Fundamentals of Computer Programming I
Sorting

2. Sequential Search Algorithm
Given: List of values v0,v1,…,vn Target value, T
Output: Location of T if in list and some signal if T is not in list
Strategy:
Use variables:
i for current location in list
Found to indicate whether T located or not
Initialize i=0, Found=false
Pass through the list sequentially

3. Pseudocode for Sequential Search
Set Found to false Set Loc to -1
Set i to 0
While not Found and i<n
if vi = T
Set Loc to i
Set Found to true
else
Set i to i+1

4. An implementation of Sequential Search

5. Can we find the largest?

6. Algorithm to Find Largest
Given: List of numbers A0,A1,…,An-1
Output: Largest value in list and its position
Strategy:
Use variables:
i for current location in list
Largest for largest value found so far
LargeLoc for position of largest found so far
Initialize Largest=A0,LargeLoc=0,i=1
Pass through the list sequentially

7. Algorithm to Find Largest (cont)
Set Largest to A0
Set LargeLoc to 0
Set i to 1
While i < n do
if Ai > Largest then
Set Largest to Ai
Set LargeLoc to i
Set i to i+1
Output Largest, LargeLoc

8. An implementation of findLargest

9. Sorting
One of the most common activities of a computer is sorting data.
Arranging data into numerical or alphabetical order for purposes of
Reports by category
Summarizing data
Searching data

10. Sorting (cont) Given: n, N0,N1,…,Nn-1
Want: Rearrangement M0,M1,…,Mn-1 where M0…  Mn-1 according to the appropriate understanding of .
There are many well-known algorithms for doing this. Preference may be due to
List size
Degree of order already present
Ease of programming
Program available

11. Sorting - Selection Sort
Strategy:
Find the largest element in list.
Swap it with last element in list.
Find next largest.
Swap it with next to last element in list
Etc.

12. Unsorted List

13. Selection Sort

14. Selection Sort - The algorithm
Set U to n-1 While U>0 LargeLoc = Largest(0,U)
Swap values at locations U and LargeLoc
Set U to U-1

15. Implementation of Selection Sort

16. Sorry, but I must take
exception to that ...