Memory Management
Any modern computer environment uses a stack as the primary memory management model for a running program. Whether it's native code (x86, Sun, VAX) or JVM, a stack is at the center of the run-time environment for Java, C++, Ada, FORTRAN, etc.
The discussion of JVM in the text is consistent with NT, Solaris, VMS, Unix runtime environments.
Each program that is running in a computer system has its own memory allocation containing the typical layout as shown below.
Bca precedence and append them to the output string; push the operator onto the stack. The order of popping is the order in the output.
5. If the current input token is '(', push it onto the stack
6. If the current input token is ')', pop off all operators and append them to the output string until a '(' is popped; discard the '('.
7. If the end of the input string is found, pop all operators and append them to the output string.
This algorithm doesn't handle errors in the input, although careful analysis of parenthesis or lack of parenthesis could point to such error determination.
Apply the algorithm to the above expressions.
Backtracking
Backtracking is used in algorithms in which there are steps along some path (state) from some starting point to some goal.
Find your way through a maze.
Find a path from one point in a graph (roadmap) to another point.
Play a game in which there are moves to be made (checkers, chess).
In all of these cases, there are choices to be made among a number of options. We need some way to remember these decision points in case we want/need to come back and try the alternative
Consider the maze. At a point where a choice is made, we may discover that the choice leads to a dead-end. We want to retrace back to that decision point and then try the other (next) alternative.
Again, stacks can be used as part of the solution. Recursion is another, typically more favored, solution, which is actually implemented by a stack.
