题解 | 点击消除

#include <iostream>
using namespace std;

int main() {
    string s;
    string ret;
    cin >> s;
    if (s.size() == 1)
        cout << s << endl;
    for (auto e : s) {
        if (ret.size() == 0) {
            ret.push_back(e);
            continue;
        }
        if (ret.back() == e) {
            ret.pop_back();
            continue;
        }
        ret.push_back(e);
    }
    if (ret.empty())
        cout << 0 << endl;
    else
        cout << ret << endl;
}
// 64 位输出请用 printf("%lld")