static object Solve()
{
var n = int.Parse(Console.ReadLine());
var s0 = Console.ReadLine().Select(c => c == 'B').ToArray();
var t = Console.ReadLine().Select(c => c == 'B').ToArray();
var s = new IndexedList <bool>();
foreach (var v in s0)
{
s.Add(v);
}
var r = 0L;
// 先行インデックス
var q = 0;
for (int i = 0; i < n; i++)
{
var v = s[i];
if (v == t[i])
{
continue;
}
if (i == n - 1)
{
return(-1);
}
q = Math.Max(q, i);
while (q + 1 < n && s[q] != s[q + 1])
{
q++;
}
if (q == n - 1)
{
return(-1);
}
r += q - i + 1;
s.RemoveAt(q);
s.RemoveAt(q);
s.Insert(i, !v);
s.Insert(i, !v);
}
if (!s.SequenceEqual(t))
{
throw new InvalidOperationException();
}
return(r);
}
public void TestAddRemoveAndClearMethods()
{
var sut = new IndexedList <ItemMetadata>();
sut.AddIndex("Idx", metadata => metadata.BlobRef);
var item1 = new ItemMetadata
{
BlobRef = Guid.NewGuid().ToString(),
Name = "Tag",
Value = "Cuba"
};
var item2 = new ItemMetadata
{
BlobRef = Guid.NewGuid().ToString(),
Name = "Tag",
Value = "beach"
};
var item3 = new ItemMetadata
{
BlobRef = Guid.NewGuid().ToString(),
Name = "Tag",
Value = "pooltable"
};
Assert.That(sut.Count, Is.EqualTo(0));
sut.Add(item1);
Assert.That(sut.Count, Is.EqualTo(1));
sut.Add(item2);
Assert.That(sut.Count, Is.EqualTo(2));
sut.Insert(1, item3);
Assert.That(sut.Count, Is.EqualTo(3));
sut.RemoveAt(2);
Assert.That(sut.Count, Is.EqualTo(2));
Assert.That(sut[0].Value, Is.EqualTo("Cuba"));
sut.Clear();
Assert.That(sut.Count, Is.EqualTo(0));
}