12 Islanders Puzzle (From Brooklyn 99)
Logic
Level
2
There are twelve identical looking islanders and a seesaw. One of the islanders weighs slightly more or less then the other 11, and you must find out which. What is the least amount of times you can use the seesaw to solve this problem?
1
2
3
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5
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This problem is similar to a balance puzzle , except this time each islander is like a coin and the seesaw is like the balance. Since the target islander weighs differently than the others, the least number of weighings for c = 1 2 islanders will be ⌈ lo g 3 ( 2 c + 1 ) ⌉ = 3 .