Virtual Labs

1. When evaluating a postfix expression, what data structure is commonly used to store intermediate results?

a: Queue Explanation

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b: Stack Explanation

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c: Linked list only Explanation

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d: Binary tree Explanation

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2. When a numeric operand is encountered while evaluating a postfix expression, what is normally done?

a: Push it onto the evaluation stack Explanation

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b: Pop two values from the stack Explanation

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c: Discard it Explanation

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d: Apply the next operator immediately Explanation

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3. When a binary operator is encountered during postfix evaluation, what is the first major action?

a: Push the operator onto the stack as an operand Explanation

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b: Pop the required operands from the stack Explanation

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c: Restart the evaluation Explanation

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d: Ignore the operator Explanation

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4. What is the postfix evaluation result of

1\ 2\ +\ 3\ 9\ -\ +\ 4\ +

a: 3 Explanation

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b: 2 Explanation

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c: 1 Explanation

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d: 4 Explanation

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5. Why does operand order matter when evaluating a non-commutative operator such as subtraction?

a: Because the first popped value is the right operand and the second popped value is the left operand. Explanation

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b: Because subtraction can always be performed in either order. Explanation

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c: Because postfix expressions do not contain subtraction. Explanation

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d: Because both operands are discarded before subtraction. Explanation

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6. What is the postfix evaluation of

5\ 2\ -\ 3\ *

a: 1 Explanation

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b: 6 Explanation

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c: 9 Explanation

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d: -9 Explanation

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7. Which postfix expression corresponds to the infix expression

(a+b)*c

a: ab+c* Explanation

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b: abc+* Explanation

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c: a+bc* Explanation

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d: *+abc Explanation

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8. For postfix expression

8\ 2\ /\ 3\ +

, what value remains on the evaluation stack at the end?

a: 7 Explanation

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b: 4 Explanation

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c: 5 Explanation

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d: 6 Explanation

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9. What is the time complexity of evaluating a postfix expression containing

n

tokens when each token is processed a constant number of times?

O(n^2)

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O(\log n)

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O(1)

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O(n)

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Infix and Postfix