Adding 4 files , each for one question

1.py

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+# ### 1.
+# Write a program that takes two inputs; 
+# one of them is a list and the other is a number,
+#  and returns the list obtained by shifting the elements in the list n places to the right (left) 
+# when n is positive (negative). Use wrap-around: if an element is shifted beyond the end of the list, 
+# then continue to shift starting at the beginning of the list.
+
+# ```
+# Example
+# Inputs>>> [1, 2, 3, 4, 5], 2
+# Output>>> [4, 5, 1, 2, 3]
+# Inputs>>> [1, 2, 3, 4, 5], -2
+# Output>>> [3, 4, 5, 1, 2]
+# ``
+
+def shift(lis, num):
+    """
+      we are going to slice the list , depending on the number n : 
+      if n =2 , we are going to slice the last two element , 
+      put them in a 'slice list', and lastly add the last 3 elements of the original list  to them
+
+    """
+    slice_list=[]
+    if num==0 or  num==len(lis) :
+        return lis
+    elif num==-1* len(lis) :
+        return sorted(lis, reverse=True)
+    elif num> len (lis):
+        return lis
+    elif num > 0 :
+        slice_list=lis [-1*num:]
+
+        return slice_list + lis[:len(lis)-num] 
+    elif num < 0   : 
+        slice_list=lis [:num-1]
+
+        return   lis[len(lis)+num-1 :] + slice_list  
+
+print (shift( [1, 2, 3, 4, 5] , 2)  )      
+
+

2.py

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+
+# ### 2.
+# Write a code snippet that inputs a sentence from the user, then uses a dictionary to
+#  summarize the number of occurrences of each letter. 
+# Ignore case, ignore blanks and assume the user does not enter any punctuation.
+#  Display a two-column table of the letters and their counts with the letters in sorted order.
+
+# ```
+# Example
+# Input >>> "This is a sample text with several words This is more sample text with some different words"
+# Output >>>
+# [('a', 4), ('d', 3), ('e', 10), ('f', 2), ('h', 4), ('i', 7), ('l', 3), ('m', 4), ('n', 1), ('o', 4), ('p', 2), ('r', 5), ('s', 10), ('t', 9), ('v', 1), ('w', 4), ('x', 2)]
+# ```
+def count_dect(string):
+    """this function takes a string an return a dictionary for every letter and its frequancy"""
+    string=string.lower()
+
+    dict={}
+    for letter in 'abcdefghijklmnopqrstuvwxyz':
+        if string.count(letter) !=0 :
+            dict[letter]= string.count(letter)
+    return dict   
+
+out=count_dect("This is a sample text with several words This is more sample text with some different words")
+print (out)

3.py

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+
+# ### 3.
+# Write a program that takes in two words as input and returns a list containing three elements,
+#  in the following order:
+# -		Shared letters between two words.
+
+# -		Letters unique to word 1.
+
+# -		Letters unique to word 2.
+
+# Each element of the output should have unique letters, and should be alphabetically sorted. Use set operations. 
+# The strings will always be in lowercase and will not contain any punctuation.
+
+# ```
+# Example
+# Input1>>> "sharp"
+# Input2>>> "soap"
+# Output>>> ['aps', 'hr', 'o']
+# ```
+def two_words(w1, w2):
+    w1=set(w1)
+    w2=set(w2)
+    lis=[]
+
+    lis.append  ("".join (sorted (w1& w2 ))  )
+    lis.append  ("".join (sorted (w1- w2 ))  )
+    lis.append  ("".join (sorted (w2-w1 ))  )
+
+    return lis
+print (two_words("sharp","soap")  )

4.py

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+
+# ### 4.
+# A palindromical prime number is a prime number that reads the same when reversed. 
+# Write a function which returns the nearest palindromical prime number less than 
+# the multiplication of all the arguments.
+
+# ```
+# Example
+# Input1>>>  some_function(2, 3, 4) 
+# Output1>>>  the nearest palindromical prime number less than 24
+# Input2>>> some_function(31, 77, 99)
+# Output2>>> the nearest palindromical prime number less than 236,313
+# ```
+def nearst_pali_prime_num(*num):
+
+    def is_prime ( num):
+        if num%2==0 and num!=2 :
+            return False
+        for i in range (3,num,2):
+            if num%i==0 :
+                return False
+        return True   
+
+
+    def is_palindromical(num):
+        string=str(num)
+        str_list=list(string)
+        str_list_rev= str_list.copy()
+        str_list_rev.reverse()
+        if str_list ==str_list_rev:
+            return True
+        return False
+
+    multiply = 1
+    for i in num:
+        multiply*=i
+
+    #now going backwards from our 'multiply' , checking every number if it is prim ? if yes > checking if it's palindromical
+    #if yes, returning it
+    print (multiply)
+    if multiply%2==0 :  #if it is even : reducing it to the nearst odd, going 2 steps backwards (for better efficiency)
+        multiply-=1
+    for i in range ( multiply, 0, -2): #we made sure we are going to start with an odd num> thus we can jump 2 in every step
+        if is_prime(i)   : 
+           if  is_palindromical(i)  :
+                    return i
+
+
+print( nearst_pali_prime_num(11))