Program to find minimum swaps required to make given anagram in python

Suppose we have two strings S and T and they are anagrams of each other. We have to find the minimum number of swaps required in S to make it same as T.

So, if the input is like S = "kolkata" T = "katloka", then the output will be 3, as can swap in this sequence [katloka (given), kotlaka, koltaka, kolkata].

To solve this, we will follow these steps −

• Define a function util() . This will take S, T, i
• if i >= size of S , then
  • return 0
• if S[i] is same as T[i], then
  • return util(S, T, i + 1)
• x := T[i]
• ret := 99999
• for j in range i + 1 to size of T, do
  • if x is same as S[j], then
    • swap S[i] and S[j]
    • ret := minimum of ret and (1 + util(S, T, i + 1))
    • swap S[i] and S[j]
• return ret
• From the main method do the following:
• return util(S, T, 0)

Let us see the following implementation to get better understanding −

Example 

Live Demo

class Solution:    def util(self, S, T, i) :       S = list(S)       T = list(T)       if i >= len(S):          return 0       if S[i] == T[i]:          return self.util(S, T, i + 1)       x = T[i]       ret = 99999;       for j in range(i + 1, len(T)):          if x == S[j]:             S[i], S[j] = S[j], S[i]             ret = min(ret, 1 + self.util(S, T, i + 1))             S[i], S[j] = S[j], S[i]       return ret          def solve(self, S, T):       return self.util(S, T, 0) ob = Solution() S = "kolkata" T = "katloka" print(ob.solve(S, T))

Input

"kolkata", "katloka"

Output

3