pascal1.py

#!/usr/bin/env python
#
# Author:  Yotam Medini  [email protected] -- Created: 2005/September/11
#
# Show a range of rows of Pascal triangle
#

import sys

level_first = 3
level_last = 12

curr_row = [1] # Top of Pascal triangle
level = 0

while level <= level_last:
    if level >= level_first:
        # Our level is now in the [level_first , level_last] range. Show it!
        i = 0
        while i < len(curr_row):
            sys.stdout.write("%d " % curr_row[i])
            i = i + 1
        sys.stdout.write("\n")

    # Compute the next row of Pascal triangle
    next_row = [1];  # 1 of the left side edge
    i = 1
    while i < len(curr_row):
        nn = curr_row[i - 1] + curr_row[i] # sum of parents
        next_row = next_row + [nn]
        i = i + 1
    next_row = next_row + [1] # 1 of the right side edge

    curr_row = next_row # Viva! new row 
    level = level + 1

sys.exit(0)