Program to check typed string is for writing target string in stuck keyboard keys or not in Python

Suppose we have two strings s and t. We want to form t, but there are some problems in the keyboard where some of characters stuck so they may be written 1 or more times. We have to check whether it's possible that typed s was meant to write t or not.

So, if the input is like s = "appppleee" t = "apple", then the output will be True.

To solve this, we will follow these steps −

• i := 0, j := 0
• s_len := size of s
• t_len := size of t
• t_last := blank string
• while j < t_len, do
  • if i is same as s_len, then
    • return False
  • if s[i] is same as t[j], then
    • t_last := t[j]
    • i := i + 1
    • j := j + 1
  • otherwise when s[i] is same as t_last, then
    • i := i + 1
  • otherwise,
    • return False
• if i < s_len, then
  • return true if all char in s[from index i to end] is same as t_last
• otherwise,
  • return True

Example

Let us see the following implementation to get better understanding −

def solve(s, t):
   i = j = 0
   s_len = len(s)
   t_len = len(t)
   t_last = ""
   while j < t_len:
      if i == s_len:
         return False
      if s[i] == t[j]:
         t_last = t[j]
         i += 1
         j += 1
      elif s[i] == t_last:
         i += 1
      else:
         return False
   if i < s_len:
      return all(char == t_last for char in s[i:])
   else:
      return True

s = "appppleee"
t = "apple"
print(solve(s, t))

Input

"appppleee", "apple"

Output

True