Expression Evaluation
Two stacks, values and operators, evaluate infix in one pass; brackets fence the operator stack.
Decision · step 2 of 13Stacks for Expressions: Evaluate infix with two stacks
'('. An opening bracket fences the operator stack.
What you will see
Tokens flow into stacks; an operator pops operands and pushes a result.
Cost
| Best | O(n) |
|---|---|
| Average | O(n) |
| Worst | O(n) |
| Space | O(n) |
How you work with it here
play it through, step one change at a time, scrub to any step, run it on your own input, predict what happens next, try operations in any order.
Screen readers: Items announce position from the top or front and value; each step announces the operation and the new top or front.
Reduced motion: Items appear or disappear in place with a crossfade instead of sliding in or out.
Before this
Taught by the same lesson
Stacks for Expressions covers these too, in the same run.