Radcliffe

from collections import Counter

def sanity_check(grid):
    if not(isinstance(grid,list)
           and len(grid) == 9
           and all(isinstance(row, list)
                   and len(row) == 9
                   for row in grid)
           and all(isinstance(elt, int)
                   and 0 <= elt <= 9

Radcliffe

#!/usr/bin/python

# 5-line fuzzer below is from Charlie Miller's
# "Babysitting an Army of Monkeys"

from os import listdir
from os.path import isfile, join

mypath = '/users/david/documents/python/pdf/'
file_list = [ mypath+f for f in listdir(mypath) if isfile(join(mypath,f)) ]

Radcliffe

# Python 2.7 program to check whether two integer powers are equal,
# WITHOUT computing the powers.
#
# Author: David Radcliffe, 1 December 2013.

ALLOW_ZERO_TO_ZERO = True
# If True, assume that 0 to the 0 is 1.
# If False, assume that 0 to the 0 is undefined.

# Return the sign of a^b. There are four possible results

Radcliffe

# Solution to a problem posted by Deomani Sharma Ramsurrun
#       David Radcliffe  11 Dec 2013
# This code is in the public domain
###########################################################

import fractions

# Generate all non-negative integer solutions to the system
#   ab + ac + ad = 6
#   ab + bc + bd = 9

Radcliffe

#!/usr/bin/env/python
#   Author: David Radcliffe (dave@gotmath.com)
#   Date: 20 December 2013
#   This code is in the public domain.

# Problem: Given a square 5x5 grid of points, find five circles that together pass through all 25 points.
# There are 21 essentially different solutions. Two solutions are considered the same if they differ only
# by a rotation or reflection. This script finds all of these solutions.
# The solutions are rendered graphically at http://www.gotmath.com/doc/fivecircles.html

Radcliffe

[ Launch: Helping Dave - new ] 8035870 by Radcliffe

Radcliffe

[ Launch: Covering a grid with circles ] 8071295 by Radcliffe

Radcliffe

[ Launch: Tributary inlet ] 9024863 by Radcliffe

Radcliffe

#!/usr/bin/env python
#
# This Python 2.7 script solves the following probability problem:

#    If 20 distinct positive integers are chosen from the range 1 - 80
#    (without replacement) what is the probability that their sum is 810?

#              Source: Kim Zafra, http://lnkd.in/bmg4AR5

# Remarks:

Radcliffe

#!/usr/bin/env python
# 
# List the numbers n such that the digits of the square of n
# can be rearranged to form exactly two other squares. 
# For example, 13 belongs to list because 13*13 = 169, and 
# the digits of 169 can be rearranged to form the squares 196 
# (= 14*14) and 961 (= 31*31); but no other squares can be formed 
# by rearranging the digits of 169.
#
# Inspired by a question of James Tanton (@jamestanton on Twitter).