Problem Description
Given a string s containing an out-of-order English representation of digits 0-9, return the digits in ascending order.
Key Insights
- Each digit from 0 to 9 has a unique character that can help identify it:
- 'z' -> 0
- 'w' -> 2
- 'u' -> 4
- 'x' -> 6
- 'g' -> 8
- The other digits can be deduced using the presence of these unique characters:
- 'o' (from one) can be used to find 1 after 0 is counted.
- 'h' (from three) can be used to find 3 after 8 is counted.
- 'f' (from five) can be used to find 5 after 4 is counted.
- 's' (from seven) can be used to find 7 after 6 is counted.
- 'i' (from nine) can be used to find 9 after 5 and 6 are counted.
- The solution requires counting the occurrences of each character and reconstructing the digits based on these counts.
Space and Time Complexity
Time Complexity: O(n), where n is the length of the string s.
Space Complexity: O(1), as the space used for counting digits is constant (fixed size of 10).
Solution
To solve the problem, we can use a frequency counter (hash table) to count occurrences of each character in the string. We then determine the counts of each digit based on the unique characters associated with them. Finally, we construct the result string by appending the digits in ascending order.