jlengrand/project_euler
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Solves Problem 28. Easy after all

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Excellent processing time

Still have to perform some good work on prime numbers! 

Signed-off-by: Julien Lengrand-Lambert <julien@lengrand.fr>
This commit is contained in:
Julien Lengrand-Lambert
2012-02-08 22:43:23 +01:00
parent a198d3fc49
commit 581c01b9ac
2 changed files with 23 additions and 7 deletions
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2
README.markdown
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@@ -39,6 +39,7 @@ Should be used in order to help future reuse of code :)
24 - What is the millionth lexicographic permutation of the digits 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9? - too long <br />
25 - What is the first term in the Fibonacci sequence to contain 1000 digits? - 0.741 <br />
27 - Find a quadratic formula that produces the maximum number of primes for consecutive values of n. - too long <br />
28 - What is the sum of both diagonals in a 1001 by 1001 spiral? - < 1 sec <br />
29 - How many distinct terms are in the sequence generated by ab for 2 a 100 and 2 b 100? - < 1 sec <br />
30 - Find the sum of all the numbers that can be written as the sum of fifth powers of their digits. - < 3 sec <br />
34 - Find the sum of all numbers which are equal to the sum of the factorial of their digits. - 30 sec <br />
@@ -52,7 +53,6 @@ Should be used in order to help future reuse of code :)
**In progress: **
26 - Find the value of d < 1000 for which 1/d contains the longest recurring cycle. <br />
28 - What is the sum of both diagonals in a 1001 by 1001 spiral? <br />
35 - How many circular primes are there below one million? <br />
39 - If p is the perimeter of a right angle triangle, {a, b, c}, which value, for p <= 1000, has the most solutions? <br />

28
e_28.py
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@@ -17,14 +17,30 @@ It can be verified that the sum of the numbers on the diagonals is 101.
What is the sum of the numbers on the diagonals in a 1001 by 1001 spiral formed in the same way?
'''
def sum_power():
def sum_diag(max_lines):
"""
Finds
Returns the sum of both diagonals of the square of max_lines size
"""
dsum = 1 # sum of diagonals
cpt = 1 # number of lines processed
val = 1 # value of the current place in the square
inc = 0 # the increment between number for one line
while cpt < max_lines:
cpt += 2
inc += 2
for corner in range(4):
val += inc
dsum += val
return 1
return dsum
if __name__ == '__main__':
# The major problem in there is to find the upper limit.
print "Answer : %d " % (sum_power())
# The major problem in there is to find the logic
#n = 1 gives 1
#n = 3 gives 3, 5, 7, 9 => +2
#n = 5 gives 13, 17, 21, 25 => +4
#n = 7 gives 31, 37, 43, 49 => +6
#n = 9 gives 57, . . .
print "Answer : %d " % (sum_diag(1001))