771-Jewels_and_Stones.ipynb

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    "771. Jewels and Stones"
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    "You're given strings J representing the types of stones that are jewels, and S representing the stones you have.  Each character in S is a type of stone you have.  You want to know how many of the stones you have are also jewels.\n",
    "\n",
    "The letters in J are guaranteed distinct, and all characters in J and S are letters. Letters are case sensitive, so \"a\" is considered a different type of stone from \"A\"."
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    "# 56 ms\n",
    "# Time: O(S*J)\n",
    "class Solution:\n",
    "    def numJewelsInStones(self, J, S):\n",
    "        \"\"\"\n",
    "        :type J: str\n",
    "        :type S: str\n",
    "        :rtype: int\n",
    "        \"\"\"\n",
    "        n=0\n",
    "        for s in S:\n",
    "            for j in J:\n",
    "                if s == j:\n",
    "                    n+=1\n",
    "                    break\n",
    "        return n"
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    "# 40 ms \n",
    "# Time: O(S+J)\n",
    "# A hash set uses O(1) to check if it contains an element\n",
    "class Solution:\n",
    "    def numJewelsInStones(self, J, S):\n",
    "        \"\"\"\n",
    "        :type J: str\n",
    "        :type S: str\n",
    "        :rtype: int\n",
    "        \"\"\"\n",
    "        n=0\n",
    "        setJ = set(J)\n",
    "        for s in S:\n",
    "            if s in setJ:\n",
    "                n+=1\n",
    "        return n"
   ]
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   "metadata": {},
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   "source": [
    "# 44 ms \n",
    "# Time: O(S+J)\n",
    "class Solution:\n",
    "    def numJewelsInStones(self, J, S):\n",
    "        \"\"\"\n",
    "        :type J: str\n",
    "        :type S: str\n",
    "        :rtype: int\n",
    "        \"\"\"    \n",
    "        setJ = set(J)\n",
    "           \n",
    "        return sum(s in setJ for s in S)"
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