Check if characters of one string can be swapped to form other in Python

Suppose we have two strings s and t, we have to check whether we can generate t by swapping the character of the s.

So, if the input is like s = "worldlloeh" t = "helloworld", then the output will be True as we can swap characters from "worldlloeh" to make "helloworld".

To solve this, we will follow these steps −

  • s_len := size of s, t_len := size of t
  • if s_len is not same as t_len, then
    • return False
  • freq := a map to store all characters and their frequencies in s
  • for i in range 0 to t_len, do
    • freq[t[i]] := freq[t[i]] - 1
    • if freq[t[i]] < 0, then
      • return False
  • return True

Let us see the following implementation to get better understanding −


 Live Demo

from collections import defaultdict
def solve(s, t):
   s_len = len(s)
   t_len = len(t)
   if (s_len != t_len):
      return False
   freq = defaultdict(int)
   for char in s :
      freq[char] += 1
   for i in range(t_len) :
      freq[t[i]] -= 1
      if freq[t[i]] < 0:
         return False
   return True
s = "worldlloeh"
t = "helloworld"
print(solve(s, t))


"worldlloeh", "helloworld"



Updated on: 30-Dec-2020


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