258. Add Digits.ipynb

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    "Given a non-negative integer num, repeatedly add all its digits until the result has only one digit.\n",
    "\n",
    "For example:\n",
    "\n",
    "Given num = 38, the process is like: 3 + 8 = 11, 1 + 1 = 2. Since 2 has only one digit, return it.\n",
    "\n",
    "Follow up:\n",
    "Could you do it without any loop/recursion in O(1) runtime?"
   ]
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    "class Solution(object):\n",
    "    def addDigits(self, num):\n",
    "        \"\"\"\n",
    "        :type num: int\n",
    "        :rtype: int\n",
    "        \"\"\"\n",
    "        if num==0:\n",
    "            return num\n",
    "        return 1+(num-1)%9"
   ]
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   "source": [
    "s=Solution()"
   ]
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       "1"
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     "execution_count": 9,
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   "source": [
    "s.addDigits(10)"
   ]
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   "source": [
    "nums = [0, 1, 0, 3, 12]"
   ]
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       "[0, 1, 3, 12, 0]"
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    "nums.pop(2)\n",
    "nums.append(0)\n",
    "nums"
   ]
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   "execution_count": 14,
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    "a=[0,0]"
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   "execution_count": 15,
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   "outputs": [
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     "data": {
      "text/plain": [
       "[0, 1, 3, 12, 0, 0]"
      ]
     },
     "execution_count": 15,
     "metadata": {},
     "output_type": "execute_result"
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   "source": [
    "nums+a"
   ]
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