Select words to maximize unique characters
Problem Description
You are provided with an array of strings, words. Your task is to select any subset of these strings and concatenate them in any order to form a single resultant string.
The primary objective is to maximize the total number of unique characters present in this final concatenated string. A critical constraint is that no character may appear more than once in the entire concatenated string.
Return any valid concatenated string (or, equivalently, the subset of words) that achieves this maximum count of unique characters.
Input
words: string[]- An array of strings.
Output
- A string
sthat satisfies:- All characters within
sare unique. - The length of
s(which represents the number of unique characters) is maximized among all valid choices.
- All characters within
Examples
words = ["un","iq","ue"]- An optimal answer could be
"uniq", which has a length of 4 unique characters.
- An optimal answer could be
words = ["aa","bc","d"]- The string
"aa"cannot be used because it contains duplicate characters ('a'). An optimal answer could be"bcd", having 3 unique characters.
- The string
Constraints and Assumptions
- The number of words in the input array,
words.length, will be between 1 and 16 (inclusive). This suggests that solutions involving backtracking or exponential complexity relative towords.lengthmight be acceptable. - The total number of characters across all words combined is moderate, typically less than or equal to 200.
- Characters are assumed to be lowercase English letters (a-z). Candidates should explicitly state this assumption if they are not provided.
AI interview prep
Core dilemma
Efficiently exploring the exponential search space of word subsets while strictly adhering to the global uniqueness constraint and maximizing the character count. The core challenge is balancing exhaustive search with intelligent pruning.
3 tradeoffs and 3 stress tests locked
Interview prep
Unlock the interviewer X-Ray rubric, tradeoff matrix, stress tests, clarifying questions, and key concepts.
Select words to maximize unique characters
Problem Description
You are provided with an array of strings, words. Your task is to select any subset of these strings and concatenate them in any order to form a single resultant string.
The primary objective is to maximize the total number of unique characters present in this final concatenated string. A critical constraint is that no character may appear more than once in the entire concatenated string.
Return any valid concatenated string (or, equivalently, the subset of words) that achieves this maximum count of unique characters.
Input
words: string[]- An array of strings.
Output
- A string
sthat satisfies:- All characters within
sare unique. - The length of
s(which represents the number of unique characters) is maximized among all valid choices.
- All characters within
Examples
words = ["un","iq","ue"]- An optimal answer could be
"uniq", which has a length of 4 unique characters.
- An optimal answer could be
words = ["aa","bc","d"]- The string
"aa"cannot be used because it contains duplicate characters ('a'). An optimal answer could be"bcd", having 3 unique characters.
- The string
Constraints and Assumptions
- The number of words in the input array,
words.length, will be between 1 and 16 (inclusive). This suggests that solutions involving backtracking or exponential complexity relative towords.lengthmight be acceptable. - The total number of characters across all words combined is moderate, typically less than or equal to 200.
- Characters are assumed to be lowercase English letters (a-z). Candidates should explicitly state this assumption if they are not provided.