1347 Minimum Number of Steps to Make Two Strings A

1347. Minimum Number of Steps to Make Two Strings Anagram

Use a frequency array/hashtable to keep track of frequencies in string s, then iterate over string t and subtract occurrences.

Finally, add up all extra occurrences that are greater than 0.

Code:

Python

class Solution:
    def minSteps(self, s: str, t: str) -> int:
        sFreq = [0] * 26
 
        for c in s:
            inx = ord('a') - ord(c)
            sFreq[inx] += 1
 
        for c in t:
            inx = ord('a') - ord(c)
            if c in s:
                sFreq[inx] -= 1
 
        ret = 0
        for i in sFreq:
            if i > 0: ret += i
 
        return ret

Big O Analysis

• Runtime The runtime complexity here is O(N) as since we would be iterating the string once.
• Memory The memory usage is O(26) since we u frequency array.

— A

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