python星号三角形不使用y *“*”

Question

I'm trying to create a iso triangle (one that starts in the middle). I have a code but the problem is that I'm not allowed to use Y* "*" 5 in my code. (The y is a variable there) Also I may only use one print statement at the end of my code. Can you please help me out.

f = int(raw_input("enter"))
for i in range(f):
    print " " * (f-i-1) + "*" * (2*i+1)

creats this triangle

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

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However, you are not allowed to use the *-operator on string and int. So for example ''***'' * 3 is not allowed, but 3 * 4 is

Answer 1

This just creates a continuous string and then prints it at the end

f = int(raw_input("Enter height: "))
s = ''
for i in xrange(f):
    for j in xrange(f-i-1):
        s += ' '
    for j in xrange(2*i+1):
        s += '*'
    s += '\n'
print s

Answer 2

This is a solution which i think is very easy to understand. You can make the parameter of range() variable, to make it more dynamic.

from __future__ import print_function

for i in range(1,12,2):
    count=(11-i)/2
    for j in xrange(count):
        print(" ",end='')
    for j in xrange(i):
        print("*",end='')
    for j in xrange(count):
        print(" ",end='')
    print(end="\n")

Answer 3

I think the best solution is using the center() string method:

f = int(raw_input("How many rows to print in the triangle? "))
star = "*"
full_string = ""
for X in xrange(f):
    star += "**" if X>0 else ""
    full_string += star.center(2*f-1) + "\n"
print full_string[:-1]

The str.center() documentation:

https://docs.python.org/2/library/string.html#string.center

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EDIT: If you can't use the print statement within the for loop, you could concatenate the string during the loop and print it at the end:

f = int(raw_input("How many rows to print in the triangle? "))
star = "*"
full_string = ""

for X in xrange(f):
    # the first row should take only one star
    star += "**" if X>0 else ""
    star2 = star.center(2*f-1)
    full_string += star2 + "\n"

# slice the string to delete the last "\n"
print full_string[:-1]

I noticed that using a for loop add a newline character. If you want to avoid this, you can slice the string before printing.

Answer 4

There is no problem with this code, i just checked it and it worked fine. If you would post the error message we might be able to help a bit more.