如何用while创建一棵圣诞树？

Question

I am currently working on some code, a student on quarantine and I am trying to solve a problem with a christmas tree but can't quite get into it.

The christmas tree has to be done with "while", I have tried but I only get half the tree.

Line of code:

lines=1
maxlines=9
while lines>=maxlines:
  print (lines*'*')
  lines+=1

What I am getting:

*
**
***
****
*****
******
*******
********
*********

What I want to get:

         *
        ***
       *****
      *******
     *********
    ***********
   *************
  ***************
 *****************
*******************

Answer 1

Here you go. This will print the tree

def tree(n):

    # total spaces
    k = 2 * n - 2

    # number of rows
    i = 0
    while i < n:
        j = 0

        # inner loop for number spaces
        while j < k:
            print(end=" ")
            j = j + 1

        # decrementing k after loop
        k = k - 1

        # number of columns
        j = 0
        while j < i + 1:
            print("* ", end="")
            j = j + 1

        # end line
        print("\r")
        i = i + 1


# Begining
n = 5
tree(n)

Answer 2

star = 1 # Star count
maxLines = 9 # Total number of lines
actualLines = 0 # Lines count

while actualLines <= maxLines:

     # print the necessary spaces before the stars   print the stars
     print(str(abs(maxLines - actualLines ) * ' ') + str(star * '*'))

     star += 2 # add 2 stars every new line
     actualLines += 1 # add 1 to the line counting

Answer 3

Firstly, your code cannot work since in your while loop the lines are never greater than the maxlines so the statement is False .

As mentioned by all the other people, you are missing spaces. Another way as close as possible to your code is this:

lines=1
maxlines=9

while lines<=maxlines:
    # print the leading spaces, the left part and the right side of the tree
    print((maxlines-lines)*' '+ lines*'*'+(lines-1)*'*')
    lines+=1

which gives:

        *
       ***
      *****
     *******
    *********
   ***********
  *************
 ***************
*****************