Check if string follows order of characters defined by a pattern or not in Python

Suppose we have a string s and another string t as pattern, we have to check whether characters in s follows the same order as determined by characters present in t. Here we have no duplicate characters in the pattern.

So, if the input is like s = "hello world" t = "hw", then the output will be True.

To solve this, we will follow these steps −

• if size of s < size of t, then
  • return False
• for i in range 0 to size of t - 2, do
  • x := t[i], y := t[i + 1]
  • right := last index of x in s
  • left := first index of x in s
  • if right is -1 or left is -1 or right > left, then
    • return False
• return True

Let us see the following implementation to get better understanding −

Example Code

Live Demo

def solve(s, t):
   if len(s) < len(t) :
      return False
 
   for i in range(len(t) - 1):
      x = t[i]
      y = t[i + 1]
 
      right = s.rindex(x)
      left = s.index(y)
 
      if right == -1 or left == -1 or right > left:
         return False

   return True

s = "hello world"
t = "hw"
print(solve(s, t))

Input

"hello world", "hw"

Output

True