Hi,

The following is my solution:

```
public bool IsIsomorphic(string s, string t)
{
int[] s1 = new int[s.Length];
int[] t1 = new int[t.Length];
bool isI = true;
if (s1.Length > 0 && t1.Length > 0)
{
s1[0] = 0;
int i = 1;
int j = 1;
for (i = 1; i < s.Length; i++)
{
if (s[i] == s[i - 1])
{
s1[i] = 1;
}
else
{
s1[i] = 0;
}
}
for (j = 1; j < t.Length; j++)
{
if (t[j] == t[j - 1])
{
t1[j] = 1;
}
else
{
t1[j] = 0;
}
}
for (int k = 0; k < s1.Length; k++)
{
if(s1[k] != t1[k])
{
isI = false;
}
}
}
else
{
isI = true;
}
return isI;
}
```

which passed 29/30 test cases but didn't pass the following test case which is ridiculously long. Shared the code with the input in google drive:

https://docs.google.com/document/d/1UkG8Rc6VItiihwvqzJdM3uMHIX-BCsslJ_lVklkxvq8/edit?usp=sharing

Any help would be great.