2020-09-04_is-leave-one-out-increasing.ipynb

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   "source": [
    "This problem was asked by Facebook.\n",
    "\n",
    "Given an array of integers, write a function to determine whether the array could become non-decreasing by modifying at most 1 element.\n",
    "\n",
    "For example, given the array `[10, 5, 7]`, you should return `true`, since we can modify the 10 into a 1 to make the array non-decreasing.\n",
    "\n",
    "Given the array `[10, 5, 1]`, you should return `false`, since we can't modify any one element to get a non-decreasing array."
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   "execution_count": 32,
   "metadata": {},
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   "source": [
    "def is_leave_one_out_increasing(nums):\n",
    "    \"\"\"Return whether the array nums could be increasing if one element was modified (or removed).\"\"\"\n",
    "    leave_one_out = True\n",
    "    for i in range(len(nums) - 1):\n",
    "        if nums[i] > nums[i+1]:\n",
    "            if not leave_one_out or not (\n",
    "                is_locally_increasing_without_index(nums, i) or \n",
    "                is_locally_increasing_without_index(nums, i+1)\n",
    "            ):\n",
    "                return False\n",
    "            leave_one_out = False\n",
    "    return True\n",
    "\n",
    "def is_locally_increasing_without_index(nums, i):\n",
    "    return i<=0 or i>=len(nums)-1 or nums[i-1] <= nums[i+1]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 33,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "True"
      ]
     },
     "execution_count": 33,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "is_leave_one_out_increasing([10, 5, 7])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 34,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "False"
      ]
     },
     "execution_count": 34,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "is_leave_one_out_increasing([10, 5, 1])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 35,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "False"
      ]
     },
     "execution_count": 35,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "is_leave_one_out_increasing([10, 10, 5, 7])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 36,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "True"
      ]
     },
     "execution_count": 36,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "is_leave_one_out_increasing([3, 10, 5, 7])"
   ]
  }
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