Evaluate Postfix With Bindings | Dataford Interview Questions

Tessian policy evaluation can represent arithmetic conditions in postfix notation so they can be processed efficiently. Given expression tokens and a mapping of variable names to integer values, evaluate the expression using the current bindings.

Tokens may be integer literals, variable names, or binary operators +, -, *, and /. Operators consume the two most recent values from the stack. For a / b, division must truncate toward zero. Every expression is valid, every referenced variable has a binding, and division by zero does not occur.

Formal Specification

Implement eval_postfix(tokens, bindings).

tokens is a list of strings in postfix order.
bindings is a dictionary mapping variable-name strings to integers.
Return the resulting integer.
Variable names contain lowercase English letters and underscores and do not begin with a digit.
A token consisting of an optional leading minus sign followed by digits is an integer literal.

Constraints

1 <= len(tokens) <= 10^4
Each integer literal and binding value is between -10^9 and 10^9
The expression contains at least one value and has valid postfix syntax
At most len(tokens) distinct variable names are referenced
Division by zero does not occur

Function Signature

def eval_postfix(tokens, bindings):

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