Leetcode Problem 736. Parse Lisp Expression

736. Parse Lisp Expression

Leetcode Solutions

Recursive Parsing with Scope Management

  1. Define a helper function evaluate_expression that takes the expression string and the current scope as arguments.
  2. If the current expression is a number, return its integer value.
  3. If the current expression is a variable, return its value from the scope.
  4. If the current expression is an operation (let, add, mult), parse the expression accordingly.
    • For let, parse variable assignments and update the scope, then evaluate the last expression with the updated scope.
    • For add, evaluate both operands and return their sum.
    • For mult, evaluate both operands and return their product.
  5. Use a stack to handle nested expressions, pushing the current scope onto the stack when entering a new scope and popping it when leaving a scope.
  6. Iterate through the expression string, updating the index as the string is parsed.
  7. Return the result of evaluating the expression.
UML Thumbnail

Iterative Parsing with Stack and Scope Management

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