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      "['a', 'b', 'c']\n",
      "['b', 'c', 'a']\n",
      "['c', 'a', 'b']\n",
      "['a', 'b', 'c']\n",
      "['b', 'c']\n",
      "['c', 'b']\n",
      "['b']\n",
      "['b']\n"
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       "3"
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   "source": [
    "# ---------------------------------------------------------------\n",
    "# python best courses https://courses.tanpham.org/\n",
    "# ---------------------------------------------------------------\n",
    "# Challenge\n",
    "# Given a string, find the length of the longest substring\n",
    "# without repeating characters.\n",
    "\n",
    "# Examples:\n",
    "# Given \"abcabcbb\", the answer is \"abc\", which the length is 3.\n",
    "# Given \"bbbbb\", the answer is \"b\", with the length of 1.\n",
    "# Given \"pwwkew\", the answer is \"wke\", with the length of 3.\n",
    "# ---------------------------------------------------------------\n",
    "# Algorithm\n",
    "\n",
    "# In summary : Form all posible sub_strings from original string, then return length of longest sub_string\n",
    "\n",
    "# - start from 1st character, form as long as posible sub string\n",
    "\n",
    "#             - Add first character to sub string\n",
    "#             - Add second character to sub string if second character not exist in sub string\n",
    "#             ...\n",
    "#             - Repeate until got a character which already exist inside sub string or \n",
    "    \n",
    "    \n",
    "# - start from 2nd character, form as long as posible sub string\n",
    "\n",
    "#             - Add first character to sub string\n",
    "#             - Add second character to sub string if second character not exist in sub string\n",
    "#             ...\n",
    "#             - Repeate until got a character which already exist inside sub string\n",
    "\n",
    "\n",
    "# ....\n",
    "\n",
    "\n",
    "# - start from final character, form as long as posible sub string\n",
    "#             - Add first character to sub string\n",
    "#             - Add second character to sub string if second character not exist in sub string\n",
    "#             ...\n",
    "#             - Repeate until got a character which already exist inside sub string\n",
    "# ---------------------------------------------------------------\n",
    "\n",
    "str = \"abcbb\"\n",
    "\n",
    "def longest_non_repeat(str):\n",
    "    \n",
    "    # init start position and max length     \n",
    "    i=0\n",
    "    max_length = 1\n",
    "\n",
    "    for i,c in enumerate(str):\n",
    "\n",
    "        # init counter and sub string value         \n",
    "        start_at = i\n",
    "        sub_str=[]\n",
    "\n",
    "        # continue increase sub string if did not repeat character         \n",
    "        while (start_at < len(str)) and (str[start_at] not in sub_str):\n",
    "            sub_str.append(str[start_at])\n",
    "            start_at = start_at + 1\n",
    "\n",
    "        # update the max length   \n",
    "        if len(sub_str) > max_length:\n",
    "            max_length = len(sub_str)\n",
    "\n",
    "        print(sub_str)\n",
    "        \n",
    "    return max_length\n",
    "\n",
    "longest_non_repeat(str)\n"
   ]
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