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Pancake Flipping Is Hard — NP Hard

Posted by samzenpus on from the sorting-a-large-stack dept.

mikejuk writes "French computer scientists have finally proved that sorting pancakes is hard — NP hard. No really — this isn't a joke. Well, it is slightly amusing but that's just because it is being presented as pancake flipping. The algorithm in question is sorting a permutation using prefix reversal — which is much easier to understand in terms of pancakes. Basically you have to sort a pancake stack by simply inserting your spatula and flipping the top part of the stack. We now know that if you can do the this in polynomial time then you have proved that P=NP."

5 of 260 comments (clear)

  1. I'm more interested... by halivar · · Score: 4, Funny

    ...in finding the exact amount of maple syrup I need to pour on a pancake stack to ensure that my bacon is accidentally covered in it.

    Because I would never intentionally put maple syrup on my bacon; that's barbaric.

    1. Re:I'm more interested... by MagicM · · Score: 4, Funny

      that artificial corn syrup crap the rest of the world calls "maple syrup" that tastes like dead beetles

      It's called "beetle juice". It's quite popular in some areas. I love me some beetle juice.

      Mmmm. Beetle juice.

    2. Re:I'm more interested... by fostware · · Score: 4, Funny

      Shhh!

      You'll summon the remake!

      --
      "We know what happens to people who stay in the middle of the road. They get run over." - Aneurin Bevan
    3. Re:I'm more interested... by Rogue+Haggis+Landing · · Score: 5, Informative

      Just go to your nearest Whole Foods (or other real food distributor) and get Grade-B maple syrup. It's not as filtered as the standard Grade-A syrup that most are used to. The flavor is incredible compared to the processed crap that everyone is used to.

      FWIW, maple syrup grades are more dependent on when the trees were tapped than on filtering and processing. (Actually, they're most dependent on what state, provincial, or national body is defining the grades, but that's a different story.) Early in the season, trees produce sap that tends to be higher in sugar and water, and lighter in flavor and color. This sap becomes grade A syrup. As the season progresses, the sap tends to become thicker, less sugary, darker, and stronger flavored, eventually becoming grade B and beyond. This varies from season to season and even from tree to tree, but is generally true.

      If you're really hardcore about your maple, you can round up some Vermont Grade C syrup, "commercial grade", that's usually used in large-scale baking operations. It's extremely thick and strong -- my wife calls it maple sludge. If you like maple, that's as close to the taste of the tree as you can get without gnawing on some bark.

  2. Re:I now understand by frisket · · Score: 5, Funny

    I love this problem. I have been reading about P=NP blah blah blah but never had a solid mental picture. This is great. I get it. Thanks. I wonder how many other mathematical misunderstandings could be cleared up with something as simple as pancakes?

    It's easy: P=pancakes and NP=no pancakes. When P=NP it means you ate them all. The problem is that P-NP != 0 because there's always some maple syrup left on the plate...