无效语法

Question

我有一种感觉，我在这里的东西很简单，但在这一个功能：

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 

我收到错误：

for item in L: 
       ^
SyntaxError: invalid syntax 

出于完整性我的整个程序是这样的：

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() 

我使用Python 2.7.1。在for循环之后我有一个分号，primes(n)函数起作用，我有一种感觉可能是愚蠢的，但我无法弄清楚它是什么导致这个无效的语法。

Answer 1

你缺少前上线一个右括号：

 L = primes(int(math.sqrt(perimeter)) #list of primes to divide the perimeter 
#    ^^  ^  ^^ 
#nesting count 1 2   3   21 

看看我们如何不与线下达成的“嵌套数” 0？

Answer 2

没有在该行的错误之前：

L = primes(int(math.sqrt(perimeter)) 

你有3个开括号，但只有两个收盘括号。

Answer 3

的错误是在线以上 - 你缺少一个右括号：

L = primes(int(math.sqrt(perimeter))) 

Answer 4

你缺少一个括号：

L = primes(int(math.sqrt(perimeter))) 
            ^
            | 
           this one 

这发生在我身上所有的时候，你只需要看看之前的行。