Python-3 : dictionary problems & Solutions

 python-3 : dictionary problems & Solutions

Problem 1. Design a Switch Case using Dictionary in python for following problem:

Take OS names as inputs : RHEL, CENTOS, UBUNTU, FEDORA, AmazonLinux, KALILinux and return the Kernel Version.

(Note:

1. Use Dummy Kernel versions as 3.0, 3.1, 3.2,3.3,3.4 & 3.5  for the OS names respectively.

2. The User Input name should be handled as case insensitiveness.

3. Default Kernel Version is 3.4.)

Solutions:

def switch(os):

   return {

       'rhel': '3.0',

       'ubuntu': '3.2',

       'centos': '3.1',

       'fedora': '3.3',

       'amazonlinux': '3.4',

       'kalilinux': '3.5'

   }.get(os.lower(), '4.0')

print(switch('RHEL'))

Problem 2. Give a List of Dict :  [{'name': 'Bibash','roll':100},{'name': 'Indu','roll':101},{'name': 'Sharmi','roll':101}], get the Student name having the highest Roll Number.

Solutions:

print(sorted(my_list, key= lambda x: x['roll'])[0])

Problem 3. Given three arrays sorted in non-decreasing order, print all common elements in these arrays.

Input:  ar1 = [1, 5, 10, 20, 40, 80]

        ar2 = [6, 7, 20, 80, 100]

        ar3 = [3, 4, 15, 20, 30, 70, 80, 120]

Output: [80, 20]

Solutions:

from collections import Counter

ar1 = [1, 5, 5,7]

ar2 = [3, 4, 5, 5, 10,7]

ar3 = [5, 5, 10, 20,7]

c1 = Counter(ar1)

c2 = Counter(ar2)

c3 = Counter(ar3)

result_dict = dict(c1.items() & c2.items() & c3.items())

res = []

for key, value in result_dict.items():

   res.extend([key]*value)

print(res)

Problem 4. Given a list of Strings, replace the value mapped by Kth value of the mapped list.

Input : test_list = [“Gfg”, “is”, “Best”], subs_dict = {“Gfg” : [5, 6, 7], “is” : [7, 4, 2]}, K = 0

Output : [5, 7, “Best”] 

Solutions: 

1. Using subs_dict 

for i in subs_dict.keys():

   test_list[ test_list.index(i) ]  = subs_dict[i][k]

print(test_list)

2. Using List Comprehension 

print( [i if i not in subs_dict else subs_dict[i][k] for i in test_list ])

Problem 5. Given a string and a number k, find the k-th non-repeating character in the string. Consider a large input string with lacs of characters and a small character set. How to find the character by only doing only one traversal of input string?

Examples:

Input : 

string = ‘bibashsahamy’

k = 3

Output : 

y

 

Solutions:

from collections import  OrderedDict

string = 'geeksforgeeks'

k = 3

my_dict = OrderedDict()

for i in string:

   my_dict[i] = my_dict.get(i, 0) + 1

print([key for (key, value) in my_dict.items() if value == 1][k-1])

Problem 6.  Given a string and a number N, we need to mirror the characters from N-th position up to the length of the string in the alphabetical order. In mirror operation, we change ‘a’ to ‘z’, ‘b’ to ‘y’, and so on.

Examples:

Input : N = 3

        engineer

Output : engrmvvi

Solutions:

my_list = list(map(chr, range(97, 123)))

my_dict = dict(zip(my_list, my_list[::-1]))

s = 'engineer'

n = 2

start = s[:3]

for i in s[3:]:

   start += my_dict[i]

print(start)

Problem 7. Given a dictionary and a character array, print all valid words that are possible using characters from the array.(Repetitions of characters are not allowed)

Examples:

Input : Dict = ["go","bat","me","eat","goal","boy", "run"]

        arr = ['e','o','b', 'a','m','g', 'l']

Output : go, me, goal.

Solutions:

from collections import Counter

Dict = ["go","bat","me","eat","goal","boy", "run"]

arr = ['e','o','o','b', 'a','m','g', 'l']

my_dict = [Counter(key) for key in Dict]

for i in my_dict:

   if all([True if arr.count(key) >= i[key] else False for key in i]):

       print(''.join(i.elements()), end=' ')

Problem 8. The input dictionary -:my_dict = {‘best’: {‘Himani’: 150, ‘Manjeet’: 10}, ‘gfg’: {‘Himani’: 210, ‘Manjeet’: 5}, ‘is’: {‘Himani’: 900, ‘Manjeet’: 8}}

Find the key where the value of the nested key ‘Himani’ is highest. 

Output: is

 

Solutions:

nested_key = 'Himani'

print(sorted( my_dict.items(), key= lambda x: x[1][nested_key], reverse=True )[0][0])

Problem 9. Given a string, find if it is ordered or not. Print True or False. 

Examples: abdey , True(because all letters in strings comes in increasing order)

Solutions

import sys

s ='abdey'

If len(s)<2:

print(True)

sys.exit()

for i in range(1,len(s)):

   if ord(s[i]) < ord(s[i-1]):

       print(False)

       break

else:

   print(True)