This puzzle is called MoveUs. It contains three missionaries and three cannibals. The red faces are cannibals and the yellow faces are missionaries. The goal is to get them all across the river.

Use the boat to carry them across. The boat can fit a maximum of two people at a time. At least one person must be in the boat for it to move.

Touch the faces to board the boat or get off the boat. Drag the boat to cross the river. At no time can a single missionary be alone with two or more cannibals on either side of the river,
or the game is over.

http://appshopper.com/games/moveus