附上代码，这代码小菜鸡也看得懂（代码已AC）

#include <bits/stdc++.h>
using namespace std;
int main() {
	string a;
	cin >> a;
	bool flag = true;
	if (a.size() == 1 || a[0] == '0')return cout << 0, 0;
	if (a[0] == '-') {
		reverse(a.begin(), a.end());
		cout << "-";
		for (int i = 0; i <= a.size() - 2; i++) {
			if (a[i] != '0')flag = false;
			if (((a[i] == '0' && a[i - 1] == '0') || (i == 0 && a[i] == '0')) && flag == true) {
				//cout << i << " " << a[i] << endl;
				continue;
			} else cout << a[i];
		}
	} else {
		reverse(a.begin(), a.end());
		for (int i = 0; i <= a.size() - 1; i++) {
			if (a[i] != '0')flag = false;
			if (((a[i] == '0' && a[i - 1] == '0') || (i == 0 && a[i] == '0')) && flag == true) {
				continue;
			} else cout << a[i];
		}
	}
	return 0;
}