How do i print a pattern like this

Question

There is a question. How do i print a pattern like this

stackoverflow
stackoverflo
 tackoverflo
 tackoverfl
  ackoverfl
  ackoverf
   ckoverf
   ckover
    kover
    kove
     ove
     ov
      v

I have tried to use for loops but failed...

str = "stackoverflow"
k = len(str)
print(str)
print(str[:(k-1)])

And I don't know how to use for loops to finish it Are there any ways without using for loops to address this problem? Thanks...

Answer 1

Another possible solution is

s = "stackoverflow"
toggle = True # If true, remove first char. Else, cut last char.
left = 0 # number of spaces to prepend
right = 0 # number of spaces to append

while s: # while s is not empty
    print(' '*left + s + ' '*right)
    if toggle:
        s = s[1:] # remove first char
        left += 1
    else:
        s = s[:-1] # remove last char
        right += 1
    toggle = not toggle

which gives output

stackoverflow
 tackoverflow
 tackoverflo 
  ackoverflo 
  ackoverfl  
   ckoverfl  
   ckoverf   
    koverf   
    kover    
     over    
     ove     
      ve     
      v