Find Minimum Required Chances to Form a String with K Unique Characters in Python

Suppose we have a string s of lowercase alphabet characters, and another number k, we have to find the minimum number of required changes in the string so that the resulting string has at most k distinct characters. In this case The change is actually changing a single character to any other character.

So, if the input is like s = "wxxyyzzxx", k = 3, then the output will be 1, as we can remove the letter "w" to get 3 distinct characters (x, y, and z).

To solve this, we will follow these steps −

• count := a map of each character in s and their frequency

• sv := sorted list of frequency values

• ans := 0

• for i in range 0 to (size of count) - k - 1, do

  • ans := ans + sv[i]

• return ans

Let us see the following implementation to get better understanding −

Example

 Live Demo

from collections import Counter
class Solution:
   def solve(self, s, k):
      count = Counter(s)
      sv = sorted(count.values())
      ans = 0
      for i in range(len(count) - k):
         ans += sv[i]
      return ans

ob = Solution()
s = "wxxyyzzxx"
k = 3
print(ob.solve(s, k))

Input

"wxxyyzzxx",3

Output

1