Comment on Programmer tries to explain binary search to the police

• Mr_Dr_Oink@lemmy.world ⁨9⁩ ⁨months⁩ ago

  Ive had a look into it and it doesn’t work if you try to do it mathmatically. You always need more than 3 gos on the seesaw.

  There is a solution in the replies to my original comemment that is the acrual solution and it works every time and ia much simpler than any grouping method.

  It involves assigning a letter to each person and then aligning that with a grid of positions "left’ or “right” or “none” on the seesaw. Over the three rounds. So, person A is on the right all three rounds person b is on the right for 2 rounds then on the left for the 3rd round.

  Yoy end up with a list of 12 patterns that do not repeat or mirror any other pattern like “LLL” “LLR” “LRR” “LR-” etc. Then you do all three rounds and compare the position the seesaw was in with thos patterns.

  If the seesaw was down on the left 2 times the down on the right the third time then you look for which person had that pattern in this case it was person B. So they are the one with a different weight and they were heavier.

  Equally, if the opposite pattern occurred. It was down on the right 2 times then down on the left for round then that is the opposite pattern of person B and does not occur anywhere else so it was person B and they were lighter.

  person:  A B C D E F G H I J K L
  
  round 1: L L L L R R R R — — — -
  
  round 2: L L R R R — — — L R L -
  
  round 3: L R R — — L R — L L — R
  

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