3-4 周期串 UVa455

#include <vector>
#include <iostream>
#include <string>
using namespace std;
bool is_circle_string(string word, int num)
{
	int n = word.size();
	for (int i = 0; i < num; i++)
		for (int j = num; j < n; j += num)
			if (word[i] != word[i + j])
				return false;
	return true;
}
int main()
{
	string word;
	cin >> word;
	int n = (int)word.size();
	int i = 2;
	for (; i <= n / 2; i++)
	{
		if (n%i == 0)
		{
			if (is_circle_string(word, i))
			{
				cout << i << endl;
				break;
			}
		}
	}
	if (i > n / 2)
	cout << n << endl;

	return 0;
}#include <vector>
#include <iostream>
#include