Question

    Consider the following stack operations. What will be

    the content of the stack after executing all the operations? Stack stack = new Stack ();  stack.push( 5 );  stack.push( 10 );  stack.pop();  stack.push( 15 );  stack.push( 20 );  stack.pop();  stack.push( 25 ); 
    A [5, 10, 25] Correct Answer Incorrect Answer
    B [5, 15, 25] Correct Answer Incorrect Answer
    C [5, 10, 15] Correct Answer Incorrect Answer
    D [5, 15, 20] Correct Answer Incorrect Answer
    E [5, 25] Correct Answer Incorrect Answer

    Solution

    The stack operates on a Last-In, First-Out (LIFO) principle. The operations are executed as follows:

    1. stack.push(5) → Stack: [5]
    2. stack.push(10) → Stack: [5, 10]
    3. stack.pop() → Removes the top element 10 . Stack: [5]
    4. stack.push(15) → Stack: [5, 15]
    5. stack.push(20) → Stack: [5, 15, 20]
    6. stack.pop() → Removes the top element 20 . Stack: [5, 15]
    7. stack.push(25) → Stack: [5, 15, 25]
    Thus, the final stack content is [5, 15, 25] . Why Other Options Are Wrong Option A: [5, 10, 25] This sequence assumes the second pop() operation does not occur. However, 20 is removed during the second pop() . Option C: [5, 10, 15] This sequence omits the addition of 25 in the final push() operation. Option D: [5, 15, 20] This sequence retains 20 in the stack, but 20 is removed during the second pop() . Option E: [5, 25] This sequence ignores the intermediate pushes of 15 and retains only 5 and 25 , which is incorrect.

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