19.1 a) False. A queue is a first-in, first-out data structure—the first item added is the first item removed. b) False. In general, trees may have as many child nodes per node as is necessary. Only binary trees are restricted to no more than two child nodes per node. c) True. d) False. Linked-list nodes are logically contiguous, but they need not be stored in a physically contiguous memory space. e) False. Those are the primary operations of a queue. The primary operations of a stack are push and pop. f) True.
19.2 a) self-referential. b)
new. c) stack. d) first-in, first-out(FIFO). e) queue. f) tree. g) binary. h) preorder.