Python 2.7：如何创建一个字典，将前n个数字映射到它们各自的正方形或立方体？

Question

I currently have this piece of code (for squares), but it doesn't seem to be working correctly:

    for n in range(len(dict)): 
       if n == 0:
          pass
       else:
          squares = (n*n)
    dict[n]=squares

Answer 1

The parameter of range() should be n , because the dictionary is probably empty when you begin. Also, dict is a builtin type in python and you shouldn't name your variables this way.

squares = {i:i*i for i in xrange(n)}

Answer 2

dict={}
for i in range(n):
    dict[i]=i*i

Answer 3

squares={}

for r in range(int(n) + 1):
     if r == 0:
         pass;
     else:
         squares[r] = (r * r)

This code will create a dictionary, look through all of the values up to n, and add the square tot he dictionary at index "r"! This code fulfills all of the requirements you asked for! Let me know if you have any questions!

Answer 4

It's not clear from the question whether dict already contains values. Also I'm not sure why you're skipping n==0 .

Assuming you have a list dict with a certain length, your code should work for all values except the first (which you're skipping), except that your last line is not indented, so it's not run inside the loop. This should do it:

for n in range(len(dict)): 
    dict[n]=n*n

Anyway I recommend a list comprehension to do this:

dict = [n*n for n in len(dict)]