#3039
Apply Operations to Make String Empty
specialist · 760 · lc medium +31 · verified · 57.4% accepted · 167 likes · top 53%
Description
You are given a string s.
Repeatedly perform the following until s is empty: scan 'a' to 'z' and remove the first occurrence of each letter that exists in s.
Return the value of s just before the final operation is applied.
For example, starting with s = "aabcbbca": after the first pass s = "abbca", after the second s = "ba", after the third s = "". The answer is "ba".
Example 1:
Input: s = "aabcbbca"
Output: "ba"
Explanation: Explained in the statement.
Example 2:
Input: s = "abcd"
Output: "abcd"
Explanation: We do the following operation:
- Remove the underlined characters s = "abcd". The resulting string is s = "".
The string just before the last operation is "abcd".
Code
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