Python 为什么 KeyError: 0
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Why KeyError: 0
提问by mistermarko
I'm attempting to solve Project Euler 21 but I'm getting KeyError: 0 which normally occurs when you refer to a dictionary key that doesn't exist. However, I thought I had solved that problem with the < 10000 condition. The error refers to the first 'if' statement in the main() function.
我正在尝试解决 Project Euler 21，但我收到 KeyError: 0 这通常发生在您引用不存在的字典键时。但是，我认为我已经用 < 10000 条件解决了这个问题。该错误指的是 main() 函数中的第一个“if”语句。
sumsdivs = {}
for i in range(1, 10000):
tmpls = []
for j in range(1, i):
if i % j == 0:
tmpls.append(j)
sumsdivs[i] = sum(tmpls)
amls = []
def main():
for i in range(1, 10000):
if sumsdivs[i] < 10000 and sumsdivs[i] == sumsdivs[sumsdivs[i]]:
if sumsdivs[i] not in amls:
amls.append(sumsdivs[i])
if sumsdivs[sumsdivs[i]] not in amls:
amls.append(sumsdivs[sumsdivs[i]])
return sum(amls)
print(main())
Any ideas?
有任何想法吗？
回答by Martijn Pieters
You insert 0for i = 1here:
你0在i = 1这里插入：
sumsdivs = {}
for i in range(1, 10000):
tmpls = []
for j in range(1, i):
if i % j == 0:
tmpls.append(j)
sumsdivs[i] = sum(tmpls)
The inner loop never runs (range(1, 1)is empty), and sum([])is 0.
内部循环从不运行（range(1, 1)为空），并且sum([])为 0。
Demo:
演示：
>>> sumsdivs = {}
>>> for i in range(1, 2):
... tmpls = []
... for j in range(1, i):
... if i % j == 0:
... tmpls.append(j)
... sumsdivs[i] = sum(tmpls)
...
>>> sumsdivs
{1: 0}
>>> sum([])
0
So sumsdivs[1]is 0, and sumsdivs[sumsdivs[0]]throws a KeyError:
sumsdivs[1]0也是如此，并sumsdivs[sumsdivs[0]]抛出一个KeyError：
>>> sumsdivs[sumsdivs[1]]
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
KeyError: 0
