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I have a feeling I'm missing something pretty simple here but, in this one function:
def triplets(perimeter):
triplets, n, a, b, c = 0 #number of triplets, a, b, c, sides of a triangle, n is used to calculate a triple
L = primes(int(math.sqrt(perimeter)) #list of primes to divide the perimeter
for item in L: #iterate through the list of primes
if perimeter % item == 0: #check if a prime divides the perimeter
n = perimeter / item
a = n**2 - (n+1)**2 #http://en.wikipedia.org/wiki/Pythagorean_triple
b = 2n*(n+1)
c = n**2 + n**2
if a+b+c == perimeter: #check if it adds up to the perimeter of the triangle
triplets = triplets + 1
return triplets
I am getting the error:
for item in L:
^
SyntaxError: invalid syntax
For completeness my entire program looks like this:
import math
def primes(n): #get a list of primes below a number
if n==2: return [2]
elif n<2: return []
s=range(3,n+1,2)
mroot = n ** 0.5
half=(n+1)/2-1
i=0
m=3
while m <= mroot:
if s[i]:
j=(m*m-3)/2
s[j]=0
while j<half:
s[j]=0
j+=m
i=i+1
m=2*i+3
return [2]+[x for x in s if x]
def triplets(perimeter):
triplets, n, a, b, c = 0 #number of triplets, a, b, c, sides of a triangle, n is used to calculate a triple
L = primes(int(math.sqrt(perimeter)) #list of primes to divide the perimeter
for item in L: #iterate through the list of primes
if perimeter % item == 0: #check if a prime divides the perimeter
n = perimeter / item
a = n**2 - (n+1)**2 #http://en.wikipedia.org/wiki/Pythagorean_triple
b = 2n*(n+1)
c = n**2 + n**2
if a+b+c == perimeter: #check if it adds up to the perimeter of the triangle
triplets = triplets + 1
return triplets
def solve():
best = 0
perimeter = 0
for i in range(1, 1000):
if triplets(i) > best:
best = triplets(i)
perimeter = i
return perimeter
print solve()
I am using Python 2.7.1. I have a semicolon after the for loop, the primes(n) function works, I have a feeling it is probably something stupid but I can't figure out what it is that is causing this invalid syntax.
257
Defining and Calling Functions You can clear up this invalid syntax in Python by switching out the semicolon for a colon. Here, once again, the error message is very helpful in telling you exactly what is wrong with the line.
i wrote the above code,and the error was syntax error , it took me about an hour to figure out that my fullstop was outside the quotes. so in my own opinion, pyflakes E syntax error actually mean syntax error; you just have to check your code again.
The general rule of thumb is that you don't modify a collection/array/list while iterating over it. Use a secondary list to store the items you want to act upon and execute that logic in a loop after your initial loop.
You are missing a closing parenthesis on the line before:
L = primes(int(math.sqrt(perimeter)) #list of primes to divide the perimeter
# ^ ^ ^ ^^
#nesting count 1 2 3 21
See how we don't reach 0 in the "nesting count" below the line?
127
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