organized

src/searching_and_sorting/searching/binary_search.py

@@ -1,6 +1,7 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
 
 
 
@@ -17,7 +18,6 @@ def binary_search(seq, key):
             hi = mid
         else:
             lo = mid + 1
-    return None
 
 
 def binary_search_rec(seq, key, lo=0, hi=None):

src/searching_and_sorting/searching/binary_search_matrix.py

@@ -1,6 +1,8 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
+
 
 ''' Searches an element in a matrix where in every row, the values are increasing from left to right, but the last number in a row is smaller than the first number in the next row.
 

src/searching_and_sorting/searching/find_item_rotated_sorted_array.py

@@ -1,25 +1,11 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
+
+
 
 ''' Given a sorted array that was rotated, find an item with binary search:
-    >>> l1 = [3, 4, 5, 6, 7, 1, 2]
-    >>> find_element_rot_array(l1, 7)
-    4
-    >>> find_element_rot_array(l1, 3)
-    0
-    >>> find_element_rot_array(l1, 4)
-    1
-    >>> find_element_rot_array(l1, 5)
-    2
-    >>> find_element_rot_array(l1, 6)
-    3
-    >>> find_element_rot_array(l1, 1)
-    5
-    >>> find_element_rot_array(l1, 2)
-    6
-    >>> find_element_rot_array(l1, 8)   
-    
 '''
 
 def find_element_rot_array(seq, key, lo=0, hi=None):
@@ -47,10 +33,12 @@ def find_element_rot_array(seq, key, lo=0, hi=None):
             return find_element_rot_array(seq, key, lo, mid)
 
 
-    
+def test_find_element_rot_array():
+    l1 = [3, 4, 5, 6, 7, 1, 2]
+    assert(find_element_rot_array(l1, 7) == 4 )
+    print("Tests passed!")
 
 
 if __name__ == '__main__':
-    import doctest
+    test_find_element_rot_array()
-    doctest.testmod()
 

src/searching_and_sorting/searching/find_max_unimodal_array.py

@@ -1,6 +1,8 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
+
 
 
 def find_max_unimodal_array(A):

src/searching_and_sorting/searching/find_sqrt_bin_search.py

@@ -1,6 +1,9 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
+
+
 
 
 

src/searching_and_sorting/searching/find_str_array_with_empty_str.py

@@ -1,21 +1,13 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
+
 
 ''' Given a sorted an array with empty strings, we use binary search to find some string (since
     the list is sorted):
     --> we deal with the empty strings with strip and then run to left and right, or move
     mid to the closed non-empty str (remember that the index must be conserved):
-    >>> l1 = ['acre', 'ball', '', 'coach', '', 'cut', '']
-    >>> find_str_array_with_empty_str(l1, l1[0])
-    0
-    >>> find_str_array_with_empty_str(l1, l1[1])
-    1
-    >>> find_str_array_with_empty_str(l1, l1[3])
-    3
-    >>> find_str_array_with_empty_str(l1, l1[5])
-    5
-    >>> find_str_array_with_empty_str(l1, 'bla')
 '''
 
 
@@ -46,7 +38,12 @@ def find_str_array_with_empty_str(seq, s1):
 
 
 
-if __name__ == '__main__':
+def test_find_str_array_with_empty_str():
-    import doctest
+    seq = ['acre', 'ball', '', 'coach', '', 'cut', '']
-    doctest.testmod()
+    key = seq[1]
+    assert(find_str_array_with_empty_str(seq, key) == 1)
+    print('Tests passed!')
 
+
+if __name__ == '__main__':
+    test_find_str_array_with_empty_str()

src/searching_and_sorting/searching/find_time_occurence_list.py

@@ -1,6 +1,7 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
 
 
 def binary_serch_counting(lst1, k, lo=0, hi=None):

src/searching_and_sorting/searching/interserction_two_arrays.py

@@ -1,6 +1,9 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
+
+
 
 ''' using sets '''
 

src/searching_and_sorting/searching/ordered_sequential_search.py

@@ -1,6 +1,9 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
+
+
 
 
 def ordered_sequential_search(seq, n):

src/searching_and_sorting/searching/searching_in_a_matrix.py

@@ -1,6 +1,9 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
+
+
 
 import numpy
 

src/searching_and_sorting/searching/sequential_search.py

@@ -1,6 +1,8 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
+
 
 
 def sequential_search(seq, n):
@@ -29,4 +31,4 @@ if __name__ == '__main__':
 Case	            Best Case	    Worst Case	    Average Case
 item is present	        1           	n	            n2
 item is not present	    n	            n           	n
-""""
+"""

src/searching_and_sorting/searching_adv/binary_search.py

@@ -1,112 +0,0 @@
-#!/usr/bin/python3
-# mari von steinkirch @2013
-# steinkirch at gmail
-
-''' A recursive and an iterative example of binary search in Python.
-    Remember: sequence must be sorted! You can return True/False or the index:
-    >>> l1 = [1, 2, 3, 4, 5, 6, 7]
-    >>> binary_search_rec(l1, 1)
-    0
-    >>> binary_search_rec(l1, 2)
-    1
-    >>> binary_search_rec(l1, 3)
-    2
-    >>> binary_search_rec(l1, 4)
-    3
-    >>> binary_search_rec(l1, 5)
-    4
-    >>> binary_search_rec(l1, 6)
-    5
-    >>> binary_search_rec(l1, 7)         
-    6
-    >>> binary_search_rec(l1, 8)       
-    >>> l1 = [1, 2, 3, 4, 5, 6]
-    >>> binary_search_rec(l1, 1)
-    0
-    >>> binary_search_rec(l1, 2)
-    1
-    >>> binary_search_rec(l1, 3)
-    2
-    >>> binary_search_rec(l1, 4)
-    3
-    >>> binary_search_rec(l1, 5)
-    4
-    >>> binary_search_rec(l1, 6)
-    5
-    >>> binary_search_rec(l1, 7) 
-    >>> l1 = [1, 2, 3, 4, 5, 6, 7]
-    >>> binary_search_iter(l1, 1)
-    0
-    >>> binary_search_iter(l1, 2)
-    1
-    >>> binary_search_iter(l1, 3)
-    2
-    >>> binary_search_iter(l1, 4)
-    3
-    >>> binary_search_iter(l1, 5)
-    4
-    >>> binary_search_iter(l1, 6)
-    5
-    >>> binary_search_iter(l1, 7)         
-    6
-    >>> binary_search_iter(l1, 8)       
-    >>> l1 = [1, 2, 3, 4, 5, 6]
-    >>> binary_search_iter(l1, 1)
-    0
-    >>> binary_search_iter(l1, 2)
-    1
-    >>> binary_search_iter(l1, 3)
-    2
-    >>> binary_search_iter(l1, 4)
-    3
-    >>> binary_search_iter(l1, 5)
-    4
-    >>> binary_search_iter(l1, 6)
-    5
-    >>> binary_search_iter(l1, 7)      
-'''
-    
-
-def binary_search_iter(seq, key):
-    hi, lo = len(seq), 0      
-    while lo < hi: # here is <!
-        mid = (hi+lo)//2
-        if key == seq[mid]: return mid
-        elif key < seq[mid]: hi = mid 
-        else: lo = mid + 1
-    return None
-
-
-def bool_binary_search_iter(seq, key):
-    hi, lo = len(seq), 0      
-    while lo < hi:
-        mid = (hi+lo)//2
-        if key == seq[mid]: return True
-        elif key < seq[mid]: hi = mid 
-        else: lo = mid + 1
-    return False
-
-
-def binary_search_rec(seq, key, lo=0, hi=None):
-    hi = hi or len(seq)
-    if hi <= lo: return None # base case: <= for odd and even numbers!
-    mid = (hi + lo) // 2    
-    if key == seq[mid]: return mid
-    elif key < seq[mid] : return binary_search_rec(seq, key, lo, mid) # include until mid-1
-    else: return binary_search_rec(seq, key, mid+1, hi)   
-
-
-def bool_binary_search_rec(seq, key, lo=0, hi=None):
-    hi = hi or len(seq)
-    if hi <= lo: return False # base case: <= for odd and even numbers!
-    mid = (hi + lo) // 2    
-    if key == seq[mid]: return True
-    elif key < seq[mid] : return bool_binary_search_rec(seq, key, lo, mid) 
-    else: return bool_binary_search_rec(seq, key, mid+1, hi)   
-
-
-    
-
-if __name__ == '__main__':
-    import doctest
-    doctest.testmod()

src/searching_and_sorting/sorting/bubble_sort.py

@@ -1,16 +1,14 @@
-#!/usr/bin/python3
+#!/usr/bin/python
 
-#  Mari von Steinkirch @ 2013
+__author__ = "Mari Wahl"
-# mari.wahl9@gmail.com
+__email__ = "marina.w4hl@gmail.com"
 
-# Bernardo Sulzbach (mafagafo) @ 2014
-# 1449441@gmail.com
 
 
 def bubble_sort(seq):
     """
     Implementation of bubble sort.
-    O(n²) and thus highly ineffective.
+    O(n2) and thus highly ineffective.
     :param seq: the sequence to be sorted.
     :return: the sorted sequence.
     """

src/searching_and_sorting/sorting/count_sort.py

@@ -1,6 +1,8 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
+
 
 
 from collections import defaultdict

src/searching_and_sorting/sorting/find_k_largest_seq_quickselect.py

@@ -1,6 +1,7 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
 
 import random
 
@@ -54,6 +55,7 @@ def test_find_k_largest_seq_quickselect():
     seq = [3, 10, 4, 5, 1, 8, 9, 11, 5]
     k = 2
     assert(find_k_largest_seq_quickselect(seq,k) == [10, 11])
+    print("Tests passed!")
 
 
 if __name__ == '__main__':

src/searching_and_sorting/sorting/gnome_sort.py

@@ -1,11 +1,10 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
 
 
-from do_benchmark import benchmark
 
-@benchmark
 def gnome_sort(seq):
     ''' sort a sequence using the gnome sort alg '''
     i = 0

src/searching_and_sorting/sorting/heap.py

@@ -1,6 +1,8 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
+
 
 class Heap(object):
     def __init__(self, data):

src/searching_and_sorting/sorting/heap_sort.py

@@ -0,0 +1,85 @@
+#!/usr/bin/python
+
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
+
+
+''' Heapsort using Pythons libraries'''
+
+import heapq
+
+def heap_sort1(seq):
+    ''' heap sort with Python's heapq '''
+    h = []
+    for value in seq:
+        heapq.heappush(h, value)
+    return [heapq.heappop(h) for i in range(len(h))]
+
+
+def test_heap_sort1():
+    seq = [3, 5, 2, 6, 8, 1, 0, 3, 5, 6, 2]
+    assert(heap_sort1(seq) == sorted(seq))
+    print('Tests passed!')
+
+
+
+''' Heapsort using my Heap class '''
+
+from heap import Heap
+
+def heap_sort2(seq):
+    heap = Heap(seq)
+
+    res = []
+    for i in range(len(seq)):
+        res.insert(0, heap.extract_max())
+
+    return res
+
+
+def test_heap_sort2():
+    seq = [3, 5, 2, 6, 8, 1, 0, 3, 5, 6, 2]
+    print heap_sort2(seq)
+    print('Tests passed!')
+
+
+''' A third way of doing heap sort '''
+
+def heap_sort3(seq):
+    for start in range((len(seq)-2)//2, -1, -1):
+        siftdown(seq, start, len(seq)-1)
+    for end in range(len(seq)-1, 0, -1):
+        seq[end], seq[0] = seq[0], seq[end]
+        siftdown(seq, 0, end - 1)
+    return seq
+
+def siftdown(seq, start, end):
+    root = start
+    while True:
+        child = root * 2 + 1
+        if child > end: break
+        if child + 1 <= end and seq[child] < seq[child + 1]:
+            child += 1
+        if seq[root] < seq[child]:
+            seq[root], seq[child] = seq[child], seq[root]
+            root = child
+        else:
+            break
+
+
+
+def test_heap_sort3():
+    seq = [3, 5, 2, 6, 8, 1, 0, 3, 5, 6, 2]
+    assert(heap_sort3(seq) == sorted(seq))
+    print('Tests passed!')
+
+
+
+
+
+
+
+if __name__ == '__main__':
+    test_heap_sort1()
+    test_heap_sort2()
+    test_heap_sort3()

src/searching_and_sorting/sorting/heap_sort1.py

@@ -1,23 +0,0 @@
-#!/usr/bin/python3
-# mari von steinkirch @2013
-# steinkirch at gmail
-
-import heapq
-
-def heap_sort1(seq):
-    ''' heap sort with Python's heapq '''
-    h = []
-    for value in seq:
-        heapq.heappush(h, value)
-    return [heapq.heappop(h) for i in range(len(h))]
-
-
-def test_heap_sort1():
-    seq = [3, 5, 2, 6, 8, 1, 0, 3, 5, 6, 2]
-    assert(heap_sort1(seq) == sorted(seq))
-    print('Tests passed!')
-
-
-if __name__ == '__main__':
-    test_heap_sort1()
-

src/searching_and_sorting/sorting/heap_sort2.py

@@ -1,24 +0,0 @@
-#!/usr/bin/python3
-# mari von steinkirch @2013
-# steinkirch at gmail
-
-from heap import Heap
-
-def heap_sort2(seq):
-    heap = Heap(seq)
-    
-    res = []
-    for i in range(len(seq)):
-        res.insert(0, heap.extract_max())
-
-    return res
-    
-    
-def test_heap_sort2():
-    seq = [3, 5, 2, 6, 8, 1, 0, 3, 5, 6, 2]
-    assert(heap_sort2(seq) == sorted(seq))
-    print('Tests passed!')
-
-
-if __name__ == '__main__':
-    test_heap_sort2()

src/searching_and_sorting/sorting/heap_sort3.py

@@ -1,36 +0,0 @@
-#!/usr/bin/python3
-# mari von steinkirch @2013
-# steinkirch at gmail
-
-def heap_sort3(seq):  
-    for start in range((len(seq)-2)//2, -1, -1):
-        siftdown(seq, start, len(seq)-1)
-    for end in range(len(seq)-1, 0, -1):
-        seq[end], seq[0] = seq[0], seq[end]
-        siftdown(seq, 0, end - 1)
-    return seq
- 
-def siftdown(seq, start, end):
-    root = start
-    while True:
-        child = root * 2 + 1
-        if child > end: break
-        if child + 1 <= end and seq[child] < seq[child + 1]:
-            child += 1
-        if seq[root] < seq[child]:
-            seq[root], seq[child] = seq[child], seq[root]
-            root = child
-        else:
-            break
-    
-   
-
-def test_heap_sort():
-    seq = [3, 5, 2, 6, 8, 1, 0, 3, 5, 6, 2]
-    assert(heap_sort3(seq) == sorted(seq))
-    print('Tests passed!')
-
-
-if __name__ == '__main__':
-    test_heap_sort3()
-

src/searching_and_sorting/sorting/insertion_sort.py

@@ -1,6 +1,8 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
+
 
 
 

src/searching_and_sorting/sorting/merge_sort.py

@@ -1,7 +1,23 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
-# steinkirch at gmail
 
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
+
+
+''' Some examples of how to implement Merge Sort in Python
+    --> RUNTIME: WORST/BEST/AVERAGE Is O(nlogn)
+    --> space complexity is O(n) for arrays
+    --> not in place, good for large arrays
+    >>> seq = [3, 5, 2, 6, 8, 1, 0, 3, 5, 6, 2]
+    >>> merge_sort(seq) == sorted(seq)
+    True
+    >>> seq2 = [3, 3, 3, 3, 3, 3, 3, 3]
+    >>> merge_sort(seq2) == sorted(seq2)
+    True
+    >>> seq3 = []
+    >>> merge_sort(seq3) == sorted(seq3)
+    True
+'''
 
 
 def merge_sort(seq):
@@ -22,12 +38,63 @@ def merge_sort(seq):
 
 
 
-
 def test_merge_sort():
     seq = [3, 5, 2, 6, 8, 1, 0, 3, 5, 6, 2]
     assert(merge_sort(seq) == sorted(seq))
     print('Tests passed!')
 
 
+'''
+    We could also divide this sort into two parts, separating
+    the merge part in another function
+'''
+
+def merge_sort_sep(seq):
+    if len(seq) < 2 : return seq    # base case
+    mid = len(seq)//2
+    left, right = None, None            # we could have declared the arrays here,
+                                        # but this would allocate unecessary extra space
+    if seq[:mid]: left = merge_sort(seq[:mid])
+    if seq[mid:]: right = merge_sort(seq[mid:])   # notice that mid is included!
+
+    return merge(left, right)      # merge iteratively
+
+def merge(left, right):
+    if not left or not right: return left or right # nothing to be merged
+    result = []
+    i, j = 0, 0
+    while i < len(left) and j < len(right):
+        if left[i] <= right[j]:
+            result.append(left[i])
+            i += 1
+        else:
+            result.append(right[j])
+            j += 1
+    if left[i:] : result.extend(left[i:])   # REMEMBER TO TO ENXTEND NOT APPEND
+    if right[j:] : result.extend(right[j:])
+    return result
+
+
+
+
+''' The two following merge functions are O(2n)=O(n) and O(n) respectively. They
+    illustrate many features in Python that '''
+def merge_2n(left, right):
+    if not left or not right: return left or right # nothing to be merged
+    result = []
+    while left and right:
+        if left[-1] >= right[-1]:
+            result.append(left.pop())
+        else:
+            result.append(right.pop())
+    result.reverse()
+    return (left or right) + result
+
+
+
+
+
+
+
 if __name__ == '__main__':
     test_merge_sort()

src/searching_and_sorting/sorting/merge_sorted_things.py

@@ -1,6 +1,7 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
 
 ''' --> In the case of two arrays: we can merge two arrays using the merge function from the merge sort
     --> we can do this for files too, merging each two

src/searching_and_sorting/sorting/quick_sort.py

@@ -1,6 +1,27 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
+
+
+''' Some examples of how to implement Quick Sort in Python
+    --> RUNTIME: BEST/AVERAGE Is O(nlogn), WORST is O(n2)
+    --> the first example is not in place, the second is in place
+    --> test with two element arrays, identical values
+
+    Quick sort in place:
+    1) select pivot as the index = 0
+    2) start pointer1 at index = 1 and pointer2 in the last element
+    3) while pointer1 < pointer2:
+        if value in pointer1 <= pivot
+            swap value in pointer1 with value in pointer2 and advanced pointer2
+        else
+            advance pointer1
+    4) now the array is like this:
+        [pivot, larger than pivot, smaller than pivot]
+    5) swap the pivot where pointer 1 stop
+    6) do recursively for [smaller] + [pivot] + [larger]
+'''
 
 
 
@@ -13,6 +34,19 @@ def quick_sort(seq):
     return left + [pivot] + right
 
 
+''' slightly different in the way we get the pivot'''
+def quick_sort(seq):
+    if len(seq) < 2 : return seq
+    mid = len(seq)//2
+    pi = seq[mid]
+    seq = seq[:mid] + seq[mid+1:]
+    left = quick_sort([x for x in seq if x <= pi])    # REMEMBER TO INCLUDE X  (OR IN RIGHT)
+    right = quick_sort([x for x in seq if x > pi])
+    return left + [pi] + right
+
+
+
+
 """ we can also divide them into two functions """
 def partition(seq):
     pi,seq = seq[0],seq[1:]
@@ -26,6 +60,23 @@ def quick_sort_divided(seq):
     return quick_sort_divided(lo) + [pi] + quick_sort_divided(hi)
 
 
+''' quick_sort in place '''
+def quick_sort_in(seq):
+    if len(seq) < 2 : return seq
+    if len(seq) == 2 and seq[0] > seq[1]:
+        seq[0], seq[1] = seq[1], seq[0]   # problems when only 2 elements because of swap
+    pivot = seq[0]  # start at the ends because we don't know how many elements
+    p1, p2 = 1, len(seq) -1   # set pointers at both ends
+    while p1 < p2: # must be < or out of range
+        if seq[p1] <= pivot: # must be <= because of pivot swap
+                seq[p1], seq[p2] = seq[p2], seq[p1]
+                p2 -= 1
+        else:
+            p1 += 1
+    seq[0], seq[p1] = seq[p1], pivot
+    return quick_sort_in(seq[p1+1:]) + [seq[p1]] + quick_sort_in(seq[:p1])
+
+
 
 
 def test_quick_sort():

src/searching_and_sorting/sorting/selection_sort.py

@@ -1,6 +1,7 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
 
 
 def selection_sort(seq):

src/searching_and_sorting/sorting/sort_anagrams_together.py

@@ -1,6 +1,7 @@
-#!/usr/bin/python3
+#!/usr/bin/python
-# mari von steinkirch @2013
+
-# steinkirch at gmail
+__author__ = "Mari Wahl"
+__email__ = "marina.w4hl@gmail.com"
 
 ''' A method to sort an array so that all the anagrams are together. Since we only
     want the anagrams to be grouped, we can use a dictionary for this task. This

src/searching_and_sorting/sorting_adv/merge_sort.py

@@ -1,70 +0,0 @@
-#!/usr/bin/python3
-# mari von steinkirch @2013
-# steinkirch at gmail
-
-''' Some examples of how to implement Merge Sort in Python 
-    --> RUNTIME: WORST/BEST/AVERAGE Is O(nlogn)
-    --> space complexity is O(n) for arrays
-    --> not in place, good for large arrays
-    >>> seq = [3, 5, 2, 6, 8, 1, 0, 3, 5, 6, 2]
-    >>> merge_sort(seq) == sorted(seq)
-    True
-    >>> seq2 = [3, 3, 3, 3, 3, 3, 3, 3]
-    >>> merge_sort(seq2) == sorted(seq2)
-    True
-    >>> seq3 = []
-    >>> merge_sort(seq3) == sorted(seq3)
-    True
-'''
-
-''' This is the main function that keep dividing the seq '''
-def merge_sort(seq):
-    if len(seq) < 2 : return seq    # base case
-    mid = len(seq)//2
-    left, right = None, None            # we could have declared the arrays here, 
-                                        # but this would allocate unecessary extra space   
-    if seq[:mid]: left = merge_sort(seq[:mid])
-    if seq[mid:]: right = merge_sort(seq[mid:])   # notice that mid is included!
-    
-    return merge(left, right)      # merge iteratively
-
-
-''' The two following merge functions are O(2n)=O(n) and O(n) respectively. They
-    illustrate many features in Python that '''
-def merge_2n(left, right):
-    if not left or not right: return left or right # nothing to be merged
-    result = []
-    while left and right:
-        if left[-1] >= right[-1]:
-            result.append(left.pop())
-        else:
-            result.append(right.pop())
-    result.reverse()
-    return (left or right) + result
-
-
-def merge(left, right):
-    if not left or not right: return left or right # nothing to be merged
-    result = []
-    i, j = 0, 0
-    while i < len(left) and j < len(right):
-        if left[i] <= right[j]:
-            result.append(left[i])
-            i += 1
-        else:
-            result.append(right[j])
-            j += 1
-    if left[i:] : result.extend(left[i:])   # REMEMBER TO TO ENXTEND NOT APPEND
-    if right[j:] : result.extend(right[j:])
-    return result
-    
-    
-   
-
-
-
-if __name__ == '__main__':
-    import doctest
-    doctest.testmod()
-
-

src/searching_and_sorting/sorting_adv/quick_sort.py

@@ -1,74 +0,0 @@
-#!/usr/bin/python3
-# mari von steinkirch @2013
-# steinkirch at gmail
-
-
-''' Some examples of how to implement Quick Sort in Python 
-    --> RUNTIME: BEST/AVERAGE Is O(nlogn), WORST is O(n2)
-    --> the first example is not in place, the second is in place
-    --> test with two element arrays, identical values
-    
-    Quick sort in place:
-    1) select pivot as the index = 0
-    2) start pointer1 at index = 1 and pointer2 in the last element
-    3) while pointer1 < pointer2:
-        if value in pointer1 <= pivot
-            swap value in pointer1 with value in pointer2 and advanced pointer2
-        else
-            advance pointer1
-    4) now the array is like this:
-        [pivot, larger than pivot, smaller than pivot]
-    5) swap the pivot where pointer 1 stop
-    6) do recursively for [smaller] + [pivot] + [larger]
-    
-    >>> seq = [3, 5, 2, 6, 8, 1, 0, 3, 5, 6, 2]
-    >>> quick_sort(seq) == sorted(seq)
-    True
-    >>> quick_sort([3, 3, 3, 3, 3, 3]) == [3, 3, 3, 3, 3, 3]
-    True
-    >>> quick_sort([]) == []
-    True
-    >>> quick_sort([2,1]) == [1, 2]
-    True
-    >>> quick_sort_in(seq) == sorted(seq)
-    True
-    >>> quick_sort_in([3, 3, 3, 3, 3, 3]) == [3, 3, 3, 3, 3, 3]
-    True
-    >>> quick_sort_in([]) == []
-    True
-    >>> quick_sort_in([2,1]) == [1, 2]
-    True
-'''
-
-def quick_sort(seq):
-    if len(seq) < 2 : return seq    
-    mid = len(seq)//2
-    pi = seq[mid]
-    seq = seq[:mid] + seq[mid+1:]  
-    left = quick_sort([x for x in seq if x <= pi])    # REMEMBER TO INCLUDE X  (OR IN RIGHT)
-    right = quick_sort([x for x in seq if x > pi])   
-    return left + [pi] + right
-    
-
-
-
-def quick_sort_in(seq): 
-    if len(seq) < 2 : return seq 
-    if len(seq) == 2 and seq[0] > seq[1]:
-        seq[0], seq[1] = seq[1], seq[0]   # problems when only 2 elements because of swap
-    pivot = seq[0]  # start at the ends because we don't know how many elements
-    p1, p2 = 1, len(seq) -1   # set pointers at both ends
-    while p1 < p2: # must be < or out of range
-        if seq[p1] <= pivot: # must be <= because of pivot swap
-                seq[p1], seq[p2] = seq[p2], seq[p1]
-                p2 -= 1
-        else:
-            p1 += 1
-    seq[0], seq[p1] = seq[p1], pivot 
-    return quick_sort_in(seq[p1+1:]) + [seq[p1]] + quick_sort_in(seq[:p1])
-
-
-
-if __name__ == '__main__':
-    import doctest
-    doctest.testmod()