There are 1000 doors. Each one labeled with a number 1-1000. A person opens all doors whose number has one as a factor (which is all of them). Then she closes all doors whose number has two as a factor. Then the person continues to change the status of the doors (opening or closing them) based...
There are 1000 doors. Each one labeled with a number 1-1000. A person opens all doors whose number has one as a factor (which is all of them). Then she closes all doors whose number has two as a factor. Then the person continues to change the status of the doors (opening or closing them) based...