Reformat The String — LeetCode 1417 Python Solution

The problem

You are given an alphanumeric string s. (Alphanumeric string is a string consisting of lowercase English letters and digits).

Example

Input

s = "a0b1c2"

Output

"0a1b2c"

Explanation

No two adjacent characters have the same type in "0a1b2c". "a0b1c2", "0a1b2c", "0c2a1b" are also valid permutations.

Python solution

class Solution:
    def reformat(self, s: str) -> str:
        a = [c for c in s if c.islower()]
        b = [c for c in s if c.isdigit()]
        if abs(len(a) - len(b)) > 1:
            return ''
        if len(a) < len(b):
            a, b = b, a
        ans = []
        for x, y in zip(a, b):
            ans.append(x + y)
        if len(a) > len(b):
            ans.append(a[-1])
        return ''.join(ans)

Complexity

Pattern: Hash Map

Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 1417. Reformat The String is filed here because the reference solution below belongs to the algorithm family this hub collects, even though its LeetCode tags point elsewhere.

The hash map guide has the Python template for the pattern and the 709 LeetCode problems that use it.

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