nested for loop to build a "0" pyramid-CodePudding

for i in range(0,7):
    for j in range(0, 7 - i):
        print(" ", end = "")
    for k in range(0, 2 * i   1):
        print("0", end = "")
    print(" ")

I saw this code online to build a pyramid contains "0", I'm confused on why do I need to pint(" ") at the very bottom for the first loop?

CodePudding user response：

You are using print with end="" to build the lines character by character without getting to a new line.

To build the pyramid, you need to skip to the next line after a line of zeros, thus the print(" ") that has a end='\n' parameter by default

output without the last print:

       0      000     00000    0000000   000000000  00000000000 0000000000000

Here is a modification of the code to show you where the separators are:

for i in range(0,7):
    for j in range(0, 7 - i):
        print(" ", end = "-")
    for k in range(0, 2 * i   1):
        print("0", end = " ")
    print("", end='=\n')

output:

 - - - - - - -0 =
 - - - - - -0 0 0 =
 - - - - -0 0 0 0 0 =
 - - - -0 0 0 0 0 0 0 =
 - - -0 0 0 0 0 0 0 0 0 =
 - -0 0 0 0 0 0 0 0 0 0 0 =
 -0 0 0 0 0 0 0 0 0 0 0 0 0 =

Here is a shorter alternative to the initial code to build the lines directly with a single loop:

n=7
for i in range(n):
    print(' '*(n-i) '0'*(2*i 1))

output:

       0
      000
     00000
    0000000
   000000000
  00000000000
 0000000000000