Question: 
Write a function to replace all spaces in the given string with character * list item * list item * list item * list item '%20'.


Model's Code:
def replace_spaces(s):
    return s.replace(" ", "%20")



Sample Correct Code:
MAX=1000;
def replace_spaces(string):
  string=string.strip()
  i=len(string)
  space_count=string.count(' ')
  new_length = i + space_count*2
  if new_length > MAX:
    return -1
  index = new_length-1
  string=list(string)
  for f in range(i-2, new_length-2):
    string.append('0')
  for j in range(i-1, 0, -1):
    if string[j] == ' ':
      string[index] = '0'
      string[index-1] = '2'
      string[index-2] = '%'
      index=index-3
    else:
      string[index] = string[j]
      index -= 1
  return ''.join(string)


Asserts:
assert replace_spaces("My Name is Dawood") == 'My%20Name%20is%20Dawood'
assert replace_spaces("I am a Programmer") == 'I%20am%20a%20Programmer'
assert replace_spaces("I love Coding") == 'I%20love%20Coding'


Tests:
Test 1 of 3: PASS
Test 2 of 3: PASS
Test 3 of 3: PASS

Test 628 of 974: 468/628 (74.52229299363057%): success