length-of-last-word.ipynb

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    "## 58. Length of Last Word\n",
    "\n",
    "Given a string `s` consisting of some words separated by some number of spaces, _return the length of the **last** word in the string_.\n",
    "\n",
    "A **word** is a maximal substring consisting of non-space characters only.\n",
    "\n",
    "\n",
    "\n",
    "**Constraints**:\n",
    "- `1 <= s.length <= 104`\n",
    "- `s` consists of only English letters and spaces `' '`.\n",
    "- There will be at least one word in `s`."
   ]
  },
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   "source": [
    "### Approach 1\n",
    "- Replace all empty spaces at end of the word with nothing (with regex)\n",
    "- Start iterating from end of string while counting until we reach whitespace"
   ]
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    {
     "name": "stdout",
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     "text": [
      "CPU times: user 3 µs, sys: 0 ns, total: 3 µs\n",
      "Wall time: 5.48 µs\n"
     ]
    }
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   "source": [
    "%time\n",
    "import re\n",
    "def lengthOfLastWord(s):\n",
    "    #replace all spaces at end of word with nothing\n",
    "    s=re.sub(r\"(\\s+$)\",\"\",s)\n",
    "\n",
    "    total=0 #total length of last word\n",
    "\n",
    "    for i in range(len(s)):\n",
    "        # if next element is space, stop and return\n",
    "        if s[-(i+1)].isspace():\n",
    "            return total\n",
    "        total+=1\n",
    "    return total\n",
    "\n",
    "\n",
    "    \n",
    "assert lengthOfLastWord(\"luffy is still joyboy\") == 6\n",
    "assert lengthOfLastWord(\"  fly me   to   the moon                                                      \") == 4\n",
    "assert lengthOfLastWord(\"o World\") == 5\n",
    "assert lengthOfLastWord(\"o World\"+\"  \"*1000) == 5\n",
    "assert lengthOfLastWord(\" \"*4000+\"test\"+\" \"*4000) == 4"
   ]
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   "source": [
    "## Approach 2\n",
    "- Strip empty spaces at end using `strip()` method of string\n",
    "- Start iterating from end of string while counting until we reach whitespace"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 32,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "CPU times: user 1e+03 ns, sys: 0 ns, total: 1e+03 ns\n",
      "Wall time: 3.1 µs\n"
     ]
    }
   ],
   "source": [
    "%time\n",
    "def lengthOfLastWord(s):\n",
    "    #replace all spaces at end of word with nothing\n",
    "    s=s.strip()\n",
    "\n",
    "    total=0 #total length of last word\n",
    "\n",
    "    for i in range(len(s)):\n",
    "        # if next element is space, stop and return\n",
    "        if s[-(i+1)].isspace():\n",
    "            return total\n",
    "        total+=1\n",
    "    return total\n",
    "\n",
    "\n",
    "    \n",
    "assert lengthOfLastWord(\"luffy is still joyboy\") == 6\n",
    "assert lengthOfLastWord(\"  fly me   to   the moon                                                      \") == 4\n",
    "assert lengthOfLastWord(\"o World\") == 5\n",
    "assert lengthOfLastWord(\"o World\"+\"  \"*1000) == 5\n",
    "assert lengthOfLastWord(\" \"*4000+\"test\"+\" \"*4000) == 4"
   ]
  }
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