1000 - 1099
1047 - Remove All Adjacent Duplicates In String (Easy)
Problem Link
https://leetcode.com/problems/remove-all-adjacent-duplicates-in-string/
Problem Statement
You are given a string s consisting of lowercase English letters. A duplicate removal consists of choosing two adjacent and equal letters and removing them.
We repeatedly make duplicate removals on s until we no longer can.
Return the final string after all such duplicate removals have been made. It can be proven that the answer is unique.
Example 1:
Input: s = "abbaca"
Output: "ca"
Explanation:
For example, in "abbaca" we could remove "bb" since the letters are adjacent and equal, and this is the only possible move. The result of this move is that the string is "aaca", of which only "aa" is possible, so the final string is "ca".Example 2:
Input: s = "azxxzy"
Output: "ay"Constraints:
1 <= s.length <= 1e5sconsists of lowercase English letters.
Approach 1: Stack
class Solution {
public:
string removeDuplicates(string s) {
// use string here instead of Stack<char>
// so that we don't need to build the final string again
string ans;
for (auto c : s) {
// if the current character is same as the last one in `ans`
// then we cannot push it to `ans`
// we remove the one in `ans`
if (ans.size() && ans.back() == c) ans.pop_back();
// otherwise, add the current character to `ans`
else ans.push_back(c);
}
return ans;
}
};