Remove Duplicate Letters
Given a string s, remove duplicate letters so that every letter appears once and only once. You must make sure your result is the smallest in lexicographical order among all possible results.
Note: This question is the same as 1081: https://leetcode.com/problems/smallest-subsequence-of-distinct-characters/
Example 1
Input
s = "bcabc"Output
"abc"Removing duplicate letters from
s can produce abc, which is the smallest lexicographical result with each letter appearing once.Example 2
Input
s = "cbacdcbc"Output
"acdb"The smallest lexicographical result containing each distinct letter from
s exactly once is acdb.Constraints
- 1 <= s.length <= 10^4
- s consists of lowercase English letters.
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