{"record":{"id":"9e40d13bb2559392","repo":"TheAlgorithms/Python","slug":"each-integral-piece-of-rod-must-have-a-correspondi","errorCode":null,"errorMessage":"Each integral piece of rod must have a corresponding price. Got n = {n} but length of prices = {len(prices)}","messagePattern":"Each integral piece of rod must have a corresponding price\\. Got n = (.+?) but length of prices = (.+?)","errorType":"validation","errorClass":"ValueError","httpStatus":null,"severity":"error","filePath":"dynamic_programming/rod_cutting.py","lineNumber":197,"sourceCode":"    Basic checks on the arguments to the rod-cutting algorithms\n\n    * `n`: int, the length of the rod\n    * `prices`: list, the price list for each piece of rod.\n\n    Throws ``ValueError``:\n        if `n` is negative or there are fewer items in the price list than the length of\n        the rod\n    \"\"\"\n    if n < 0:\n        msg = f\"n must be greater than or equal to 0. Got n = {n}\"\n        raise ValueError(msg)\n\n    if n > len(prices):\n        msg = (\n            \"Each integral piece of rod must have a corresponding price. \"\n            f\"Got n = {n} but length of prices = {len(prices)}\"\n        )\n        raise ValueError(msg)\n\n\ndef main():\n    prices = [6, 10, 12, 15, 20, 23]\n    n = len(prices)\n\n    # the best revenue comes from cutting the rod into 6 pieces, each\n    # of length 1 resulting in a revenue of 6 * 6 = 36.\n    expected_max_revenue = 36\n\n    max_rev_top_down = top_down_cut_rod(n, prices)\n    max_rev_bottom_up = bottom_up_cut_rod(n, prices)\n    max_rev_naive = naive_cut_rod_recursive(n, prices)\n\n    assert expected_max_revenue == max_rev_top_down\n    assert max_rev_top_down == max_rev_bottom_up\n    assert max_rev_bottom_up == max_rev_naive\n","sourceCodeStart":179,"sourceCodeEnd":215,"githubUrl":"https://github.com/TheAlgorithms/Python/blob/f5988cc09713315817df6a7e327e258013a94440/dynamic_programming/rod_cutting.py#L179-L215","documentation":"Raised by the rod-cutting argument checker when n exceeds len(prices). Every integral piece length 1..n needs a price entry, so prices must have at least n items (index 0 is the price of a length-1 piece, etc.). Otherwise the algorithms would read past the end of the price list.","triggerScenarios":"Calling top_down_cut_rod(7, [6, 10, 12, 15, 20, 23]) (n=7 > 6 prices), or bottom_up_cut_rod with n derived from a different list than prices. Equality n == len(prices) is fine.","commonSituations":"Appending to a rod-length request without extending the price table; using a truncated price list (e.g. CSV row missing columns); mixing up argument order so a longer list lands in n's position.","solutions":["Ensure len(prices) >= n; extend the price list or reduce n.","Double-check argument order — the signature is (n, prices), not (prices, n).","If prices come from a file, validate the row length matches the maximum rod length before calling."],"exampleFix":"# before\ntop_down_cut_rod(7, [6, 10, 12, 15, 20, 23])  # ValueError\n\n# after\nprices = [6, 10, 12, 15, 20, 23, 25]\ntop_down_cut_rod(7, prices)","handlingStrategy":"validation","validationCode":"def valid_rod_args(n: int, prices: list[float]) -> bool:\n    return n >= 0 and len(prices) >= n","typeGuard":null,"tryCatchPattern":"try:\n    top_down_cut_rod(n, prices)\nexcept ValueError as e:\n    if 'corresponding price' in str(e):\n        n = min(n, len(prices))\n    else:\n        raise","preventionTips":["Derive n from the price list itself: n = len(prices) when possible.","Pin argument order — signature is (n, prices).","Validate CSV-loaded price rows have the full length."],"tags":["dynamic-programming","input-validation","argument-mismatch"],"backgroundTag":null,"analyzedSha":"f5988cc09713315817df6a7e327e258013a94440","analyzedAt":"2026-08-14T17:30:07.041Z","schemaVersion":2},"datasetVersion":"2026-08-15T22:17:37.221Z"}