"three-pipe problem" meaning in English

{
  "etymology_text": "From the Sherlock Holmes stories of Arthur Conan Doyle, in which the detective would smoke one or more pipes while pondering the solution to a mystery.",
  "forms": [
    {
      "form": "three-pipe problems",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "three-pipe problem (plural three-pipe problems)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "A particularly complex or challenging problem or puzzle."
      ],
      "id": "en-three-pipe_problem-en-noun-PD-UVREv",
      "links": [
        [
          "complex",
          "complex"
        ],
        [
          "challenging",
          "challenging"
        ]
      ],
      "related": [
        {
          "word": "one-banana problem"
        }
      ]
    }
  ],
  "word": "three-pipe problem"
}

{
  "etymology_text": "From the Sherlock Holmes stories of Arthur Conan Doyle, in which the detective would smoke one or more pipes while pondering the solution to a mystery.",
  "forms": [
    {
      "form": "three-pipe problems",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "three-pipe problem (plural three-pipe problems)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "related": [
    {
      "word": "one-banana problem"
    }
  ],
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "Pages with 1 entry",
        "Pages with entries"
      ],
      "glosses": [
        "A particularly complex or challenging problem or puzzle."
      ],
      "links": [
        [
          "complex",
          "complex"
        ],
        [
          "challenging",
          "challenging"
        ]
      ]
    }
  ],
  "word": "three-pipe problem"
}