The Japanese IQ Test is an online flash game that requires the player to move a mother, a father, two sons, two daughters, a criminal and a policeman across a river on a raft. The raft can only hold two people at a time, and only the mother, father and policeman know how to operate it. The mother cannot be left alone with either of the sons, nor can the father be left alone with either of the daughters, and the criminal cannot be left with anyone unless the policeman is present.
Move the policeman and criminal across together, then the policeman back alone.
The policeman and one son cross together, then the policeman brings the criminal back. One son is across the river.
The father and the remaining son cross, then the father returns alone. Both sons are now across the river.
The father and mother travel across together, then the mother returns alone, leaving the father and both sons on the other side of the river.
The policeman and criminal cross together, and the father returns alone. Both sons, the policeman, and the criminal are across the river.
The father and mother cross, then the mother returns alone, leaving both sons, the father, the policeman, and the criminal on the other side.
The mother and one daughter cross, then the policeman returns with the criminal. The father, the mother, both sons, and one daughter are across the river.
The policeman brings the remaining daughter across, leaving the criminal alone, then returns by himself to bring the criminal across. Voila, you have solved the "Japanese IQ Test."