CFGs and Parse Trees
Computer Science
Level
1
What expression does this parse tree generate?
The conext-free grammar wikipedia page
x + y * x - z * y / x + x
( x + y ) * x - z * y / ( x + x )
( x + y ) + x - z + y - ( x + x )
x + y + z * y + x * x
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Start at the leaves of the tree and work your way up left to right. The left-most leaves are x and y and those are connected by an "+" node. This is connected to a "( )" node, so those go in parentheses. Keep following the tree this way until you hit the next branching node, which is (in this case) "S * S" where the first "S" is "(x + y)" and the second "S" is "x" --> so this yields "(x + y) * x" and so on.