review problems. what is the big o? i
TRANSCRIPT
Review Problems
Review Problems
• What is the Big O?
i <- N
j <- 1
loop
exitif(i <= 0)
loop
exitif(j > M)
j <- j + 1
endloop
i < i - 1
endloop
Review problems
• Circle and Identify the 3 parts of recursion:
Function Fact returnsa Num(N iot in Num)
if(N = 0) then
Fact returns 1
else
Fact returns N * Fact(N - 1)
endif
endfunction // Fact
Review problems
• Circle and Identify the 3 parts of recursion:
Function Fact returnsa Num(N iot in Num)
if(N = 0) then
Fact returns 1
else
Fact returns N * Fact(N - 1)
endif
endfunction // Fact
Check for termination
Call self
Move onestep closer
Review Problems
• Recall that a leaf is a node in a binary tree with no children.
• Write a module that when passed a pointer to a binary tree will return the number of leaves.
• The module should use recursion
Leaves
Function Leaves returnsa Num
(current iot Ptr toa TNode)
if(current = NIL) then
Leaves returns 0
elseif(current^.left = NIL AND
current^.right = NIL) then
Leaves returns 1
else
Leaves returns Leaves(current^.right) +
Leaves(current^.left)
endif
endfunction // Leaves
Review Problems
• How many “time chunks” will be required to run this algorithm on 2 processors?
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I II III
Review Problems
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S4
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I II
Review Problems
• Write a module to convert an unsorted linked list to a sorted linked list.
• Use data structure conversion as opposed to a sort algorithm such as Bubble Sort or Merge Sort
Solution
• Recall that for this type problem you will typically need three modules:– A standard linked list AddInOrder module– A modified linked list traversal module
• modified to keep track of pointer to new list
– A startup module
Review problems
Algorithm Pain
a,b,c iot Char
a <- ‘b’
b <- ‘c’
c <- ‘a’
Agony(c,a,’b’)
print(a,c,b)
b <- funky(a,c)
print(a,b,c)
endalgorithm
Procedure Agony(a iot in/out Char, b iot out Char, c iot in Char)
t iot Charif(c = ‘c’) then
c <- ‘d’t <- bb <- aa <- t
elseb <- aa <- ‘b’
endifendprocedureFunction funky returnsa Char
(x,y isoftype in Char)if(x = y) then
funky returns ‘a’else
finky returns ‘b’endif
endfunction
Review problems
• Write a vector class• It should be generic and support (at least) the
following methods in the public section• AddToEnd• AddAt(nth)• Remove(nth)• Size• Get(nth)
class Vector(DT)
public
Procedure AddToEnd(din iot in DT)
// PPP
Procedure AddAt(nth iot in Num, din iot in DT)
// PPP
Procedure Remove(nth iot in Num)
// PPP
Function Size returnsa Num()
// PPP
Function Get returnsa DT(nth iot in Num)
// PPP
Procedure Initialize()
// PPP
protected
Node definesa record
data iot DT
next iot Ptr toa Node
endrecord
head isoftype Ptr toa Node
count isoftype Num
Procedure AddToEnd(din iot in DT)
AddToEndHelper(head, din)
endprocedure // AddToEnd
Procedure AddToEndHelper
(cur iot in/out Ptr toa Node, din iot in DT)
// PPP
if(cur = NIL) then
cur = new(Node)
cur^.data <- din
cur^.next <- NIL
count <- count + 1
else
AddToEndHelper(cur^.next, din)
endif
endprocedure // AddToEndHelper
Procedure AddAt(nth iot in Num, din iot in DT)
AddAtHelper(head, nth, din, 1)
endprocedure // AddAt
Procedure AddAtHelper(cur iot in/out Ptr toa Node,
nth iot in Num, din iot in DT,kount iot in Num)
// PPP
temp iot Ptr toa Node
if(cur = NIL OR nth = kount) then
temp <- new(Node)
temp^.data <- din
temp^.next <- cur
cur <- temp
count <- count + 1
else
AddAtHelper(cur^.next, nth, din, kount + 1)
endif
endprocedure // AddAtHelper
Procedure Remove(nth iot in Num)
RemoveHelper(head, nth, 1)
endprocedure // Remove
Procedure RemoveHelper(cur iot in/out Ptr toa Node,
nth iot in Num, kount iot in Num)
// PPP
if(cur <> NIL) then
if(nth = kount) then
cur <- cur^.next
count <- count - 1
else
RemoveHelper(cur^.next, nth, kount + 1)
endif
endif
endprocedure // RemoveHelper
Function Size returnsa Num() Size returns count endfunction // Size
Function Get returnsa DT(nth iot in Num) Get returns GetHelper(head, nth, kount) endfunction
Function GetHelper returnsa DT (cur iot in Ptr toa Node, nth, kount iot in Num) // Precon: User must not request item > Size ** // PP if(nth = kount) then GetHelper returns cur^.data else GetHelper returns GetHelper (cur^.next, nth, kount + 1) endif endfunction // GetHelper
Procedure Initialize()
head <- NIL
count <- 0
endprocedure // Initialize
endclass // Vector
Review problems• Use the generic Vector class you just wrote to write a
baseball roster program.• It should manage baseball player records consisting of
– Name– Position
• It should support the following operations– Add a player– Remove a player– Add a player at position N– Print a roster (only if there are 9 players otherwise print
an error message)• Assume that the record is named Player• Assume that you have modules called
– Procedure GetPlayer(data isoftype out Player)– Procedure PrintPlayer(data isoftype in Player)
Procedure Menu(Choice iot out Num)
print(“1-Add a player”)
print(“2-Remove a player”)
print(“3-Add a player at position N”)
print(“4-Print a roster”)
print(“5-Quit”)
read(Choice)
endprocedure // Menu
Player definesa record
Name iot String
Position iot String
endrecord // Player
Procedure GetPlayer(data isoftype out Player)
Procedure PrintPlayer(data isoftype in Player)
TEAMSIZE is 9
Algorithm Roster uses Vector(DT)
Team isoftype Vector(Player) // Make the Vector!!! Choice iot Num
Loop Menu(Choice) exitif(Choice = 5) if(Choice = 1) then Add(Team) elseif(Choice = 2) then Remove(Team) elseif(Choice = 3) then AddAt(Team) elseif(Choice = 4) then PrntRoster(Team) endifendalgorithm // Roster
Procedure Add(Team iot in/out Vector(Player)) temp iot Player GetPlayer(temp) Team.AddToEnd(temp)endprocedure // Add
procedure Remove(Team iot in/out Vector(Player)) i iot Num print(“Line number to remove?”) read(i)
Team.Remove(i)endprocedure // Remove
Procedure AddAt(Team iot in/out Vector(Player)) i iot Num temp iot Player print(“Enter at what line number”) GetPlayer(temp) Team.AddAt(i, temp)endprocedure // AddAt
Procedure PrntRoster(Team iot in/out Vector(Player)))i iot Num
if(Team.Size() <> TEAMSIZE) print(“Wrong size team”) else i < 1 Loop exitif(i > TEAMSIZE) PrintPlayer(Team.Get(i)) i <- i + 1 endloop endifendprocedure // PrntRoster