力扣1047. 删除字符串中的所有相邻重复项

class Solution {
public:
    string removeDuplicates(string s) {
        string result;
        for(auto c : s) {
            if(result.empty() || result.back() != c) result.push_back(c);
            else result.pop_back();
        }
        return result;
    }
};