How hard is LeetCode 423. Reconstruct Original Digits from English?

LeetCode 423. Reconstruct Original Digits from English is rated Medium on LeetCode.

What is the time complexity of LeetCode 423. Reconstruct Original Digits from English?

The Python solution on this page runs in O(n).

What is the space complexity of LeetCode 423. Reconstruct Original Digits from English?

The Python solution on this page uses O(n) auxiliary space.

What topics does LeetCode 423. Reconstruct Original Digits from English cover?

LeetCode 423. Reconstruct Original Digits from English is tagged Hash Table, Math and String on LeetCode.

Reconstruct Original Digits from English — LeetCode 423 Python Solution

MediumHash TableMathString

Problem: #423
Pattern: Math and Number Theory
Reading time: 3 min
Source: leetcode.com

The problem

Given a string s containing an out-of-order English representation of digits 0-9, return the digits in ascending order.

Example

Input: s = "owoztneoer"
Output: "012"

Python solution

Python

class Solution:
    def originalDigits(self, s: str) -> str:
        counter = Counter(s)
        cnt = [0] * 10

        cnt[0] = counter['z']
        cnt[2] = counter['w']
        cnt[4] = counter['u']
        cnt[6] = counter['x']
        cnt[8] = counter['g']

        cnt[3] = counter['h'] - cnt[8]
        cnt[5] = counter['f'] - cnt[4]
        cnt[7] = counter['s'] - cnt[6]

        cnt[1] = counter['o'] - cnt[0] - cnt[2] - cnt[4]
        cnt[9] = counter['i'] - cnt[5] - cnt[6] - cnt[8]

        return ''.join(cnt[i] * str(i) for i in range(10))

Complexity

Measure	Complexity
Time	O(n)
Space	O(n) auxiliary

Pattern: Math and Number Theory

Find the closed form, the invariant, or the modular identity — and skip the loop entirely. LeetCode 423. Reconstruct Original Digits from English is filed here because LeetCode tags it Math, which is the vocabulary this hub collects.

The math and number theory guide has the Python template for the pattern and the 485 LeetCode problems that use it.

Frequently asked questions

How hard is LeetCode 423. Reconstruct Original Digits from English?: LeetCode 423. Reconstruct Original Digits from English is rated Medium on LeetCode.
What is the time complexity of LeetCode 423. Reconstruct Original Digits from English?: The Python solution on this page runs in O(n).
What is the space complexity of LeetCode 423. Reconstruct Original Digits from English?: The Python solution on this page uses O(n) auxiliary space.
What topics does LeetCode 423. Reconstruct Original Digits from English cover?: LeetCode 423. Reconstruct Original Digits from English is tagged Hash Table, Math and String on LeetCode.