Stack
Q21.
Assume that the operators +, -, x , are left associative and ^ is right associative. the order of precedence (from highest to lowest) is ^, x , +, -. The postfix expression corresponding to the infix expression a + b x c-d^e^f isQ22.
The best data structure to check whether an arithmetic expression has balanced parenthesis is a:Q23.
The five items: A, B, C, D, and E are pushed in a stack, one after other starting from A. The stack is popped four items and each element is inserted in a queue. The two elements are deleted from the queue and pushed back on the stack. Now one item is popped from the stack. The popped item isQ25.
Which of the following permutations can be obtained in the output (in the same order) using a stack assuming that the input is the sequence 1, 2, 3, 4, 5 in that order?Q26.
A program attempts to generate as many permutations as possible of the string, 'abcd' by pushing the characters a,b,c,d in the same order onto a stack, but it may pop off the top character at any time. Which one of the following strings CANNOT be generated using this program?Q27.
The best data structure to check whether an arithmetic expression has balanced parentheses is aQ28.
The five items: A, B, C, D, and E are pushed in a stack, one after other starting from A. The stack is popped four items and each element is inserted in a queue. The two elements are deleted from the queue and pushed back on the stack. Now one item is popped from the stack. The popped item isQ29.
Stack A has the entries a, b, c (with a on top). Stack B is empty. An entry popped out of stack A can be printed immediately or pushed to stack B. An entry popped out of the stack B can be only be printed. In this arrangement, which of the following permutations of a, b, c are not possible?Q30.
Let S be a stack of size n \geq 1. Starting with the empty stack, suppose we push the first n natural numbers in sequence, and then perform n pop operations. Assume that Push and Pop operation take X seconds each , and Y seconds elapse between the end of the one such stack operation and the start of the next operation. For m \geq 1, define the stack-life of m as the time elapsed from the end or Push (m) to the start of the pop operation that removes m from S . The average stack-life of an element of this stack is