52 lines
1.3 KiB
Python
52 lines
1.3 KiB
Python
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# This function sorts a list (like list.sort)
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# using the insertion sort algorithm.
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# Modify it to accept a key= keyword argument that works like in list.sort.
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def insertionSort(lst):
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# Traverse elements starting at position 1
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for i in range(1, len(lst)):
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# We know that lst[:i] is sorted
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x = lst[i] # x is the element to insert next
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# Elements in lst[:i] that are > x must move one position ahead
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j = i - 1
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while j >= 0 and lst[j] > x:
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lst[j + 1] = lst[j]
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j -= 1
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# Then put x in the last emptied slot
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lst[j + 1] = x
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# Now we know that lst[:i+1] is sorted
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return
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def main():
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# Original list
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lst0 = ["paulo", "augusto", "maria", "paula", "bernardo", "tito"]
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print("lst0", lst0)
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# sort in lexicographic order:
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lst = lst0.copy()
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insertionSort(lst)
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print("lst1", lst)
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assert lst == sorted(lst0)
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# sort by length (requires key= argument):
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lst = lst0.copy()
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insertionSort(lst, key=len)
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print("lst2", lst)
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assert lst == sorted(lst0, key=len)
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# sort by length, than lexicographic order:
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myorder = lambda s:(len(s), s)
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lst = lst0.copy()
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insertionSort(lst, key=myorder)
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print("lst3", lst)
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assert lst == sorted(lst0, key=myorder)
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print("All tests OK!")
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if __name__ == "__main__":
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main()
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