Compsci 101 Exam 2 Sec02 Fall 2017

Problem 1 Sec 2

['S', 'A']
['S', 'A', ['T', 'R']]
['G', 'U', 'C', 'B', 'W']
['C', 'S', 'U']
['C', 'U']
[4, 7, 8]
[3, 4, 7, 8]
[7, 8]
set([8, 1])                   # elements in any order is ok
set([1, 2, 8, 9])             # elements in any order is ok  
set([9, 2])                   # elements in any order is ok
['A', 'F', 'H', 'K']
['A', 'F', 'H', 'K', 'P']
[2, 4, 4, 5, 7]
[('A', 2), ('F', 4), ('H', 5), ('K', 4), ('P', 7)]

Part B:
[40, 10, 50, 70]              # elements in any order is ok
[1, 3, 2, 4]                  # elements in any order is ok
4

Problem 2 Sec 2

Part A:
['car', 'airplane', 'train', 'skates']

Part B:
['ci', 'eh', 'sh']

Part C:

result = [word[:3] + word[:3] for word in phrase.split() if len(word)%3 == 0]

ALT

result = [word[0:3]*2 for word in phrase.split() if len(word)%3 == 0]

Part D:

def howMany(fruitlist):
    d = {}
    for item in fruitlist:
        [name, fruit] = item.split(":")
        if name not in d:
            d[name] = 0
        d[name] += 1
    return sorted(d.items())
    
Problem 3 Sec 2
Part A

def setup(filename):
    f = open(filename)
    ans = []
    for item in f:
        item = item.strip()
        alist = item.split(":")
        first = alist[:2]
        values = alist[2:]
        values = [int(num) for num in values]
        alist = first + values
        ans.append(alist)
    return ans

Part B Sec 2:
def offers(data, student):  
    ans = []
    for item in data:
        if student == item[1]:
            total = sum(item[2:])
            ans.append( (total, item[0]) )
    ans = sorted(ans)
    flip = [(t[1],t[0]) for t in ans]     # swap two items in each tuple
    return flip

Problem 4 Sec 2
Part A: Sec 2 

def clubs(data):
    ans = []
    for item in data:
        ans.append(item[0])
    return sorted(set(ans))

Part 4B: Sec 2

# students in leadership level or higher in at least one club
def studentsClubs(data, num):
    ansset = set([])
    for item in data:
        student = item[1]
        lead = int(item[4])
        if lead >= num:
            ansset.add(student)
    return sorted(ansset)

Part 4C: Sec 2
     
# return those clubs in common
def clubsCommon(data, clist):
    ans = set([])
    for item in data:
        club = item[0]
        ans.add(club)
    common = ans & set(clist)
    return sorted(list(common))    # or return  sorted(common)  

Part 4D: Sec 2

def dictNamesToMeetings(data):
    d = {}
    for item in data:
        club = item[0]
        person = item[1]
        meetings = int(item[3])
        if person not in d:
            d[person] = []
        d[person].append((club, meetings))       
    return d

Part 4E: Sec 2

def nameMostMeetings(data):
    maxnum = 0
    maxname = ""
    maxlist = []
    d = dictNamesToMeetings(data)
    for (name,mlist) in d.items():
        x = sum([num for (club,num) in mlist])
        if x > maxnum:
            maxnum = x
            maxname = name
            maxlist = [club for (club,num) in mlist ]
    return (maxname, sorted(maxlist) ) 

Part 4F: Sec 2 

# return the name of the student in the most clubs
def studentMost(data):
    d = {}
    for item in data:
        stud = item[1]
        if stud not in d:            ALT: if stud not in d:
            d[stud] = 0                      d[stud] = 1
        d[stud] += 1                      else:
                                             d[stud] += 1 
    # find max
    maxstud = ""
    maxnum = 0
    for (stud,num) in d.items():
        if num > maxnum:
            maxstud = stud
            maxnum = num
    return maxstud

ALT Soln

def studentMost(data):
    d = {} 
    for item in data:
        stud = item[1]
        if stud not in d:  
            d[stud] = 1    
        else:
            d[stud] += 1   
                           
    sortlist = sorted([(val,key) for (key,val) in d.items()])
    # max is at the end of the sorted list
    return sortlist[-1][1]