CODE

public class Solution {
  public string MinWindow(string s, string t) {

    int i = 0;
    char[] toCheck = t.ToArray();

    string currSubStr = "";
    string lastSubStr = "";
    while (i < s.Length)
    {
      bool keepSliding = false;            
      int j = i;
         char[] tArr = t.ToArray();
      string tCopy = new string(tArr);

      /* first instance of match in t */
      if (tCopy.Contains(s[j])) keepSliding = true;
      /* slide till end or all chars in t found */
      while (keepSliding)
      {
        currSubStr += s[j];
        if (tCopy.Contains(s[j]))
        {
          int index = tCopy.IndexOf(s[j]);
          tArr[index] = '.';
          tCopy = new string(tArr);
        }
        j++;
        if (j > s.Length-1 || allCheckedCheck(tArr)) break;
      }

      /* if all chars in t found and substr new min, update */
      if (allCheckedCheck(tArr)) {
        if (lastSubStr.Equals("") || 
            currSubStr.Length < lastSubStr.Length)
        {
          lastSubStr = lastSubStr.Remove(0,lastSubStr.Length);
          lastSubStr += currSubStr;                    
        }
      }
      currSubStr = currSubStr.Remove(0,currSubStr.Length);
      /* move on to next char in s and repeat */
      i++;
    }
    return lastSubStr;
  }

  bool allCheckedCheck(char[] toBeChecked)
  {
    foreach (var l in toBeChecked)
      if (l != '.')
        return false;
      return true;
  }
}