donnemartin/interactive-coding-challenges · error · ValueError

array must have 3 or more ints

Error message

array must have 3 or more ints

What it means

Raised by Solution.max_prod_three_nlogn when the array has fewer than 3 elements. The maximum product of three numbers is undefined without at least three values, so the method raises ValueError('array must have 3 or more ints') before sorting.

Source

Thrown at online_judges/prod_three/prod_three_solution.ipynb:157

   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Code"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "class Solution(object):\n",
    "\n",
    "    def max_prod_three_nlogn(self, array):\n",
    "        if array is None:\n",
    "            raise TypeError('array cannot be None')\n",
    "        if len(array) < 3:\n",
    "            raise ValueError('array must have 3 or more ints')\n",
    "        array.sort()\n",
    "        product = 1\n",
    "        for item in array[-3:]:\n",
    "            product *= item\n",
    "        return product\n",
    "\n",
    "    def max_prod_three(self, array):\n",
    "        if array is None:\n",
    "            raise TypeError('array cannot be None')\n",
    "        if len(array) < 3:\n",
    "            raise ValueError('array must have 3 or more ints')\n",
    "        curr_max_prod_three = array[0] * array[1] * array[2]\n",
    "        max_prod_two = array[0] * array[1]\n",
    "        min_prod_two = array[0] * array[1]\n",
    "        max_num = max(array[0], array[1])\n",
    "        min_num = min(array[0], array[1])\n",
    "        for i in range(2, len(array)):\n",
    "            curr_max_prod_three = max(curr_max_prod_three,\n",

View on GitHub (pinned to 358f2cc604)

Solutions

1. Check len(array) >= 3 before calling and skip/handle short inputs.
2. Catch ValueError at the call site and treat it as 'insufficient data'.
3. Fix the data pipeline so it guarantees at least three samples.

Example fix

# before
best = Solution().max_prod_three_nlogn([1, 2])  # ValueError

# after
nums = [1, 2]
best = Solution().max_prod_three_nlogn(nums) if len(nums) >= 3 else None

if len(array) >= 3:
    best = Solution().max_prod_three_nlogn(array)
else:
    best = None  # insufficient data

def has_three_ints(x):
    return isinstance(x, list) and len(x) >= 3 and all(isinstance(v, int) for v in x)

try:
    best = Solution().max_prod_three_nlogn(array)
except ValueError as e:
    if '3 or more' in str(e):
        best = None
    else:
        raise

When it happens

Trigger: Calling max_prod_three_nlogn([1, 2]) or with an empty list.

Common situations: Small or filtered-down datasets (e.g. filtering outliers leaves 2 items); test edge cases with short arrays.

Related errors

• prices must have at least two values
• rows and cols cannot be negative
• sentence cannot be None
• rows and cols cannot be None
• num_pairs cannot be < 0

AI-assisted analysis of donnemartin/interactive-coding-challenges@358f2cc604 (2026-08-28). Data as JSON: /api/errors/c5e1229acccf66fc. Report an issue: GitHub.