
Algorithmic Thinking ◾ 231
e process of evaluating a formula is oen expressed as a tree struc-
ture as shown in Figure8.11. e tree structure is useful because it explic-
itly indicates how the operators are related to each other and how the
operands are fed into each operator. e ordering of the operators is also
explicitly dened; the ordering proceeds from bottom to top and le to
right. Each operator is drawn as a blue circle where the inputs are denoted
using arrows that ow into the circle. e operands that occur in the for-
mula are colored yellow and the values that are produced by operators are
colored green.
8.2.2.2.5 Par ...