added more questions

Author: xcao21

100+ Python challenging programming exercises.txt

@@ -2040,13 +2040,337 @@ t = Timer("for i in range(100):1+1")
 print t.timeit()
 
 #----------------------------------------#
+Question:
+
+Please write a program to shuffle and print the list [3,6,7,8].
+
+
+
+Hints:
+Use shuffle() function to shuffle a list.
+
+Solution:
+
+from random import shuffle
+li = [3,6,7,8]
+shuffle(li)
+print li
+
+#----------------------------------------#
+Question:
+
+Please write a program to shuffle and print the list [3,6,7,8].
+
+
+
+Hints:
+Use shuffle() function to shuffle a list.
+
+Solution:
+
+from random import shuffle
+li = [3,6,7,8]
+shuffle(li)
+print li
+
+
+
+#----------------------------------------#
+Question:
+
+Please write a program to generate all sentences where subject is in ["I", "You"] and verb is in ["Play", "Love"] and the object is in ["Hockey","Football"].
+
+Hints:
+Use list[index] notation to get a element from a list.
+
+Solution:
+
+subjects=["I", "You"]
+verbs=["Play", "Love"]
+objects=["Hockey","Football"]
+for i in range(len(subjects)):
+    for j in range(len(verbs)):
+        for k in range(len(objects)):
+            sentence = "%s %s %s." % (subjects[i], verbs[j], objects[k])
+            print sentence
+
+
+#----------------------------------------#
+Please write a program to print the list after removing delete even numbers in [5,6,77,45,22,12,24].
+
+Hints:
+Use list comprehension to delete a bunch of element from a list.
+
+Solution:
+
+li = [5,6,77,45,22,12,24]
+li = [x for x in li if x%2!=0]
+print li
+
+#----------------------------------------#
+Question:
+
+By using list comprehension, please write a program to print the list after removing delete numbers which are divisible by 5 and 7 in [12,24,35,70,88,120,155].
+
+Hints:
+Use list comprehension to delete a bunch of element from a list.
+
+Solution:
+
+li = [12,24,35,70,88,120,155]
+li = [x for x in li if x%5!=0 and x%7!=0]
+print li
+
+
+#----------------------------------------#
+Question:
+
+By using list comprehension, please write a program to print the list after removing the 0th, 2nd, 4th,6th numbers in [12,24,35,70,88,120,155].
+
+Hints:
+Use list comprehension to delete a bunch of element from a list.
+Use enumerate() to get (index, value) tuple.
+
+Solution:
+
+li = [12,24,35,70,88,120,155]
+li = [x for (i,x) in enumerate(li) if i%2!=0]
+print li
+
+#----------------------------------------#
+
+Question:
+
+By using list comprehension, please write a program generate a 3*5*8 3D array whose each element is 0.
+
+Hints:
+Use list comprehension to make an array.
+
+Solution:
+
+array = [[ [0 for col in range(8)] for col in range(5)] for row in range(3)]
+print array
+
+#----------------------------------------#
+Question:
+
+By using list comprehension, please write a program to print the list after removing the 0th,4th,5th numbers in [12,24,35,70,88,120,155].
+
+Hints:
+Use list comprehension to delete a bunch of element from a list.
+Use enumerate() to get (index, value) tuple.
+
+Solution:
+
+li = [12,24,35,70,88,120,155]
+li = [x for (i,x) in enumerate(li) if i not in (0,4,5)]
+print li
+
+
+
+#----------------------------------------#
+
+Question:
+
+By using list comprehension, please write a program to print the list after removing the value 24 in [12,24,35,24,88,120,155].
+
+Hints:
+Use list's remove method to delete a value.
+
+Solution:
+
+li = [12,24,35,24,88,120,155]
+li = [x for x in li if x!=24]
+print li
+
+
+#----------------------------------------#
+Question:
+
+With two given lists [1,3,6,78,35,55] and [12,24,35,24,88,120,155], write a program to make a list whose elements are intersection of the above given lists.
 
+Hints:
+Use set() and "&=" to do set intersection operation.
+
+Solution:
+
+set1=set([1,3,6,78,35,55])
+set2=set([12,24,35,24,88,120,155])
+set1 &= set2
+li=list(set1)
+print li
+
+#----------------------------------------#
+
+With a given list [12,24,35,24,88,120,155,88,120,155], write a program to print this list after removing all duplicate values with original order reserved.
+
+Hints:
+Use set() to store a number of values without duplicate.
+
+Solution:
+
+def removeDuplicate( li ):
+    newli=[]
+    seen = set()
+    for item in li:
+        if item not in seen:
+            seen.add( item )
+            newli.append(item)
+
+    return newli
+
+li=[12,24,35,24,88,120,155,88,120,155]
+print removeDuplicate(li)
+
+
+#----------------------------------------#
+Question:
+
+Define a class Person and its two child classes: Male and Female. All classes have a method "getGender" which can print "Male" for Male class and "Female" for Female class.
+
+Hints:
+Use Subclass(Parentclass) to define a child class.
+
+Solution:
+
+class Person(object):
+    def getGender( self ):
+        return "Unknown"
+
+class Male( Person ):
+    def getGender( self ):
+        return "Male"
+
+class Female( Person ):
+    def getGender( self ):
+        return "Female"
+
+aMale = Male()
+aFemale= Female()
+print aMale.getGender()
+print aFemale.getGender()
+
+
+
+#----------------------------------------#
+Question:
+
+Please write a program which count and print the numbers of each character in a string input by console.
+
+Example:
+If the following string is given as input to the program:
+
+abcdefgabc
+
+Then, the output of the program should be:
+
+a,2
+c,2
+b,2
+e,1
+d,1
+g,1
+f,1
+
+Hints:
+Use dict to store key/value pairs.
+Use dict.get() method to lookup a key with default value.
+
+Solution:
+
+dic = {}
+s=raw_input()
+for s in s:
+    dic[s] = dic.get(s,0)+1
+print '\n'.join(['%s,%s' % (k, v) for k, v in dic.items()])
+
+#----------------------------------------#
+
+Question:
+
+Please write a program which accepts a string from console and print it in reverse order.
+
+Example:
+If the following string is given as input to the program:
+
+rise to vote sir
+
+Then, the output of the program should be:
+
+ris etov ot esir
+
+Hints:
+Use list[::-1] to iterate a list in a reverse order.
+
+Solution:
+
+s=raw_input()
+s = s[::-1]
+print s
 
 #----------------------------------------#
 
+Question:
+
+Please write a program which accepts a string from console and print the characters that have even indexes.
+
+Example:
+If the following string is given as input to the program:
+
+H1e2l3l4o5w6o7r8l9d
 
+Then, the output of the program should be:
+
+Helloworld
 
+Hints:
+Use list[::2] to iterate a list by step 2.
+
+Solution:
+
+s=raw_input()
+s = s[::2]
+print s
 #----------------------------------------#
 
 
+Question:
+
+Please write a program which prints all permutations of [1,2,3]
+
+
+Hints:
+Use itertools.permutations() to get permutations of list.
+
+Solution:
+
+import itertools
+print list(itertools.permutations([1,2,3]))
+
 #----------------------------------------#
+Question:
+
+Write a program to solve a classic ancient Chinese puzzle: 
+We count 35 heads and 94 legs among the chickens and rabbits in a farm. How many rabbits and how many chickens do we have?
+
+Hint:
+Use for loop to iterate all possible solutions.
+
+Solution:
+
+def solve(numheads,numlegs):
+    ns='No solutions!'
+    for i in range(numheads+1):
+        j=numheads-i
+        if 2*i+4*j==numlegs:
+            return i,j
+    return ns,ns
+
+numheads=35
+numlegs=94
+solutions=solve(numheads,numlegs)
+print solutions
+
+#----------------------------------------#
+
+