built-in sequence type example

Author: AstinCHOI

general_problems/arrays_strings_lists/reversing_words_string.py

@@ -0,0 +1,79 @@
+# EXAMPLE NUMBER 1
+def reverser(string1, p1=0, p2=None):
+    if len(string1) < 2:
+        return string1
+    p2 = p2 or len(string1)-1
+    while p1 < p2:
+        aux = string1[p1]
+        string1[p1] = string1[p2]
+        string1[p2] = aux
+        p1 += 1
+        p2 -= 1
+
+def reversing_words_setence_logic(string1):
+    reverser(string1)
+    p = 0
+    start = 0
+    final = []
+    while p < len(string1):
+        if string1[p] == u"\u0020":
+            reverser(string1,start,p-1)
+            start = p+1
+        p += 1
+    reverser(string1,start,p-1)
+
+    return "".join(string1)
+
+# EXAMPLE NUMBER 2 AND 3 USING PYTHON AWESOMESAUCE
+def reversing_words_setence_py(str1):
+    ''' reverse the words in a sentence'''
+    words = str1.split()
+    rev_set = " ".join(reversed(words))
+    return rev_set
+
+def reversing_words_setence_py2(str1):
+    """
+    Reverse the order of the words in a sentence.
+    :param string: the string which words will be reversed.
+    :return: the reversed string.
+    """
+    words = str1.split(' ')
+    words.reverse()
+    return ' '.join(words)
+
+# EXAMPLE 4, VERY SILLY, USING BRUTE FORCE
+def reverse_words_brute(string):
+    """
+    Reverse the order of the words in a sentence.
+    :param string: the string which words will be reversed.
+    :return: the reversed string.
+    """
+    word, sentence = [], []
+    for character in string:
+        if character != ' ':
+            word.append(character)
+        else:
+            # So we do not keep multiple whitespaces. An empty list evaluates to False.
+            if word:
+                sentence.append(''.join(word))
+            word = []
+    # So we do not keep multiple whitespaces. An empty list evaluates to False.
+    if word != '':
+        sentence.append(''.join(word))
+    sentence.reverse()
+    return ' '.join(sentence)
+
+# TESTS
+def test_reversing_words_sentence():
+    str1 = "Buffy is a Vampire Slayer"
+    assert(reversing_words_setence_py(str1) == "Slayer Vampire a is Buffy")
+    assert(reversing_words_setence_py2(str1) == "Slayer Vampire a is Buffy")
+    assert(reverse_words_brute(str1) == "Slayer Vampire a is Buffy")
+    assert(reversing_words_setence_logic(list(str1)) == "Slayer Vampire a is Buffy")
+
+    print("Tests passed!")
+
+
+if __name__ == '__main__':
+    test_reversing_words_sentence()
+

general_problems/lists/runtime_lists_with_timeit_module.py

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+def test1():
+    l = []
+    for i in range(1000):
+        l = l + [i]
+def test2():
+    l = []
+    for i in range(1000):
+        l.append(i)
+
+def test3():
+    l = [i for i in range(1000)]
+
+def test4():
+    l = list(range(1000))
+
+if __name__ == '__main__':
+    import timeit
+    t1 = timeit.Timer("test1()", "from __main__ import test1")
+    print("concat ",t1.timeit(number=1000), "milliseconds")
+    t2 = timeit.Timer("test2()", "from __main__ import test2")
+    print("append ",t2.timeit(number=1000), "milliseconds")
+    t3 = timeit.Timer("test3()", "from __main__ import test3")
+    print("comprehension ",t3.timeit(number=1000), "milliseconds")
+    t4 = timeit.Timer("test4()", "from __main__ import test4")
+    print("list range ",t4.timeit(number=1000), "milliseconds")