3223. Minimum Length of String After Operations
Description
You are given a string s
.
You can perform the following process on s
any number of times:
- Choose an index
i
in the string such that there is at least one character to the left of indexi
that is equal tos[i]
, and at least one character to the right that is also equal tos[i]
. - Delete the closest character to the left of index
i
that is equal tos[i]
. - Delete the closest character to the right of index
i
that is equal tos[i]
.
Return the minimum length of the final string s
that you can achieve.
Example 1:
Input: s = "abaacbcbb"
Output: 5
Explanation:
We do the following operations:
- Choose index 2, then remove the characters at indices 0 and 3. The resulting string is
s = "bacbcbb"
. - Choose index 3, then remove the characters at indices 0 and 5. The resulting string is
s = "acbcb"
.
Example 2:
Input: s = "aa"
Output: 2
Explanation:
We cannot perform any operations, so we return the length of the original string.
Constraints:
1 <= s.length <= 2 * 105
s
consists only of lowercase English letters.
Solutions
Solution 1: Counting
We can count the occurrences of each character in the string, and then iterate through the count array. If a character appears an odd number of times, then $1$ of that character remains in the end; if a character appears an even number of times, then $2$ of that character remain. We can sum the remaining counts of all characters to get the final length of the string.
The time complexity is $O(n)$, where $n$ is the length of the string $s$. The space complexity is $O(|\Sigma|)$, where $|\Sigma|$ is the size of the character set, which is $26$ in this problem.
1 2 3 4 |
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 |
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 |
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 |
|
1 2 3 4 5 6 7 8 9 10 11 |
|