In an act of kindness, King gave four prisoners the possibility of being released. He ordered the four of them to be buried to the neck, with only their heads sticking out of the earth. Looking ahead, unable to move, they see that there is a wall between prisoner A and B and know that the four are wearing hats – two white and two black – but they don’t know what color their own hat is.
Prisoner A and B see only their respective sides of the wall, C sees man B and D sees prisoners B and C. They have no communication with each other and will be taken back to jail within 10 minutes. . The only chance of being saved is if one of them accepts the color of the hat they are wearing. If he makes a mistake, they all return to prison. Minutes later, one of them screams and hits the color.
Which one shouted the color of his own hat?
How was he sure about the color of his hat?
国王给4个犯人一个被释放的机会。4个犯人脖子以下全被埋在泥土里，他们的头只能往前看，不能转动。犯人A和犯人B之间隔了一堵墙，所有犯人都知道他们中间有2个人戴黑帽子，2个人戴白帽子，但是大家都不知道自己帽子的颜色。
犯人A和犯人B只能看见墙，犯人C可以看见B，犯人D可以看见B和C。他们不能相互交流，10分钟以后他们会被送回监狱。他们唯一被释放的机会就是有人能正确喊出他自己帽子的颜色。如果他喊错，那么全体回监狱。几分钟后，其中一个人正确喊出了他自己帽子的颜色。
请问：谁喊对了帽子颜色？为什么？
