代码

#include<string>
#include<cmath>
using namespace std;

void (int* ptr,int n) {
	for (int i = 0; i < n; i++)
	{
		if (*(ptr + i) == 0) {
			*(ptr + i) = 1;
			for (int k = 0; k < i; k++)
			{
				*(ptr + k) = 0;
			}
			break;
		}
	}
}

string reverse(string a) {
	int n = a.size();
	string b(a);
	for (int i = 0; i < n; i++)
	{
		b[i] = a[n - i - 1];
	}
	return b;
}

int main() {
	string s;
	cin >> s;
	int n = s.size();
	int* ptr = new int[n]();
	int sum = 0;
	for (int i = 0; i < (pow(2, n) - 1); i++)
	{
		move(ptr, n);
		string a = "";
		for (int j = 0; j < n; j++)
		{
			if (ptr[j] == 1) {
				a += s[j];
			}
		}
		if (a == reverse(a)) {
			sum += 1;
		}
	}
	delete[] ptr;
	cout << sum << endl;
	return 0;
}