Each node in the tree represents a single computational state, while each edge represents a transition to the next possible computation.
The leaves of the tree are called output nodes.
In a computation tree for a decision problem, each output node is labeled Yes or No.
and the path for x ends in node labeled yes, then the input x is accepted.
[2] The depth of the computation tree for a given input is the computation time for the Turing machine on that input.