3. Lecture 01: DS & Algorithms:2013
Iftikhar
Traversal
• Traversing:
• In traversing operation, each element of an array is accessed
exactly once for processing. This is called visiting of the array.
• To compute the sum of values of each element of an array.
• Display values of each element of an array.
• Algorithm:
• 1. Set k=LB
• 2. Repeat Step 3 and Step 4 while k<=UB
• 3. Apply PROCESS to LA[K]
• 4. Set K=K+1
• 5. [End of Step 2 loop]
• 6. Exit
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4. Lecture 01: DS & Algorithms:2013
Iftikhar
Traversal Algo
• Find the Number NUM of years during which
more than 300 automobiles were sold.
• 1. Set NUM=0
• 2. Repeat for K=1932 to 1984
• 3. If AUTO[K]>300, then: Set NUM=NUM +1.
• 4. [End of Loop]
• 5. Return
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5. Lecture 01: DS & Algorithms:2013
Iftikhar
Inserting
• In inserting operation , new data items are added or inserted into
any location of an empty or filled array.
• In case of empty array, new values are stored in empty locations.
• In case of filled array , old values are either replaced by new values
or pushed backward to make room for new values.
• It is very easy to insert data at the end of array(Why?).
• Without disturbing the data of other elements of the array.
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6. Lecture 01: DS & Algorithms:2013
Iftikhar
Inserting
• Algorithm- Inserting value at specified location
1. Set J=N
2. Repeat Step 3 and Step 4 while J>=K
3. Set LA[J+1]=LA[J]
4. Set J=J-1
5. [End of Step 2 loop]
6. Set LA[K]=ITEM
7. Set N=N+1
8. Exit
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7. Lecture 01: DS & Algorithms:2013
Iftikhar
Deletion
• Deleting item from a specified Location
• When the data item is removed from a specified location within an
array, the items from that location up to the end of array are moved
one location towards the beginning of the array.
• Algorithm:
1. Set ITEM=LA[K]
2. Repeat for J=K to N-1
3. Set LA[J]=LA[J+1]
4. [End of loop]
5. Set N=N-1
6. Exit
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8. Lecture 01: DS & Algorithms:2013
Iftikhar
Search
• The Process of finding a specific data item and its location in an
array is called searching.
• Successful- If found
• Terminated- If data item found
• Unsuccessful
• Searching Operation in data structures is used for data modification
together with inserting, deleting and updating.
• For example , when a data item is to be deleted , it is first searched
and then deleted, if found.
• The most commonly used search algorithms are as follows.
• i. Sequential Search
• Ii. Binary Search
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9. Lecture 01: DS & Algorithms:2013
Iftikhar
Search
• The sequential search is a slow process and is used for only small lists of data.
• The Method is not recommended for large amount of data because some more
efficient methods are available for large and complex searches.
• Algorithm: Linear Search
1. SET LOC=-1
2. INPUT N values into array XYZ
3. INPUT VAL
4. Repeat Step 5 For I= 1 TO N
5. IF VAL = XYZ[I] THEN
6. LOC=1
7. Print “value found at location”, LOC
8. Exit
9. END IF
10. If LOC=-1 THEN
11. PRINT ”Value is not Found”
12. END IF
13. EXIT
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10. Lecture 01: DS & Algorithms:2013
Iftikhar
Search(Binary Search)
1. Set BEG=LB, END=UB and MID=INT((BEG+ENG)/2
2. Repeat Steps 3 and 9 while BEB<=ENG and DATA[MID]!=ITEM
3. If ITEM<DATA[MID],then
4. Set END=MID-1
5. Else
6. Set BEG=MID+1
7. END IF
8. Set MID=INT((BEG+END))/2
9. END OF LOOP
10. If DATA[MID]=ITEM, then
11. Set LOC=MID
12. Else
13. Set LOC=NULL
14. END IF
15. EXIT
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