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mbaltrusitis/pascals_triangle.py

Created March 19, 2017 20:54
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  1. mbaltrusitis created this gist Mar 19, 2017.
    42 changes: 42 additions & 0 deletions pascals_triangle.py
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,42 @@
    #!/usr/bin/env python3

    import sys


    def PascalsTriangle(row):
    max_row = int(row)
    triangle = []
    current_row = 0

    while current_row < max_row:
    # These first two cases are short circuits that allow us to ignore
    # the invisible 0s that pad the 1s and can't ignore in these 2 rows
    if current_row == 0:
    members = [1]
    elif current_row == 1:
    members = [1, 1]
    # proceed as normal now that we are passed the first 2 rows
    else:
    pr_index = current_row - 1 # previous row's index
    members = [1]
    members += [triangle[pr_index][x] + triangle[pr_index][x+1]
    for x in range(pr_index)]
    members += [1]
    triangle.append(members)
    current_row += 1

    return triangle


    if __name__ == "__main__":
    try:
    count = sys.argv[1]
    tri = PascalsTriangle(count)
    except Exception as err:
    sys.stderr.write(("\nUsage: pt.py <int>\n"
    "Example: pt.py 3\n"
    "\t[[1]\n"
    "\t[1, 1]\n"
    "\t[1, 2, 1]]\n"))

    print("\n".join([str(row) for row in tri])) # print it pretty, print it niiiice