void RandomString(char* a, int n)
{
	const char* box = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefjhijklmnopqrstuvwxyz0123456789";
	int boxLength = strlen(box);

	for (int i = 0; i < n; i++)
	{
		a[i] = box[rand() % boxLength];
	}
	a[n] = '\0';
	cout << a << endl;
}

void QuickSortString(char* a, int left, int right) {
	int i, j, x, t;
	x = a[(left + right) / 2]; i = left; j = right;
	do {
		while (a[i] < x) i++;
		while (a[j] > x) j--;
		if (i <= j) {
			t = a[i]; a[i] = a[j]; a[j] = t;
			i++; j--;
		}
	} while (i < j);
	if (left < j) QuickSortString(a, left, j);
	if (i < right) QuickSortString(a, i, right);
}

int SequentialSearchChar(char* a, int n, char x)
{
	for (int i = 0; i < n; i++)
		if (a[i] == x) return 1;
	return 0;
}
void MenuCau2()
{
	char x;
	int sl, n;
	cout << "Nhap vao so phan tu cua mang: ";
	cin >> n;
	char* a = new char[n + 1];
nhaplai:
	system("cls");
	cout << "Cau 2:" << endl;
	cout << "1.Create Arr \n2.Sort \n3.Search \n0.Exit" << endl;
	cout << "Nhap vao lua chon cua ban: ";
	cin>>sl;
	switch (sl)
	{
	case 1:
		cout << "Mang da duoc tao la: ";
		RandomString(a, n);
		cout << endl;
		system("pause");
	case 2:
		cout << "Truoc khi sap xep: " << a << endl;
		QuickSortString(a, 0, n - 1);
		cout << "Sau khi sap xep: " << a << endl;
	case 3:
		cout << "Nhap vao ki tu ban can tim: ";
		cin >> x;
		if (SequentialSearchChar(a, n, x) == 1)
			cout << x << " co trong mang!" << endl;
		else
			cout << x << " khong co trong mang"<<endl;
	case 0:
		break;
	default:
		cout << "Nhap sai lua chon!Vui long nhap lai!" << endl;
		goto nhaplai;
	}
}