Is this the Hardest Logic Puzzle in the World?
Hardest Riddle in the World
The Pacific RiddleThere is an island in the middle of the pacific that is inhabited by only two types of people: ones with triangles in the middle of their foreheads, and ones with circles. These two tribes have lived together for thousands of years but rarely talk because there is a mystical taboo - they can never mention what they see on each others forehead, and can never look at their own. Anyone who breaks that taboo will be killed instantly by the others.
Although they have small fishing boats, they don't have the means to leave for another island, and have understandably becoming rather irritated with each other.
However, there is hope. There is a prophesy amongst the islanders that a boat will come which is big enough to take them all off the island forever. Never to make things easy for themselves, however, the prophesy also says that only those with circles on their foreheads can go. Those with triangles must stay. If anyone with a triangle on their forehead steps on to the boat, all will be lost and the island, with the boat, will sink forever.
All is just dandy, until one day a large boat turns up. It moors up in the bay, and the single occupant comes ashore.
The people of the island all gather to welcome the sailor, excited that at last the prophesy is unfolding. Looking at the crowd for the first time, the sailor exclaims, "Heh, I can see someone with a triangle on their forehead. Way cool!"
The crowd instantly kill him.
They then stop. They look at the boat. It's far enough in that they could only leave on a high tide, and there's only one of those a day. But at least it's big - it can take 100 people. They count themselves - there are 100 of them on the island.
There's been enough bloodshed, and no-one wants to guess. But how are they to work out who goes, and who stays?
See the Answer to the Hardest Riddle.