A program attempts to generate as many permutation as possible of the string “abcd” by pushing the character 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 a strings CANNOT be generated using this program?

Assume that the operators +, -, ×, are left associative and ^ is right associative. The order of precedence (from highest to lowest) is ^, ×, +, -. The postfix expression corresponding to the infix expression a + b×c-d^e^f is

The best data structure to check whether an arithmetic expression has balanced parentheses is a

Two matrices M₁ and M₂ are to be stored in arrays A and B respectively. Each array can be stored either in row-major or column-major order in contiguous memory locations. The time complexity of an algorithm to compute M₁$$\times$$ M₂ will be