Solve expression evaluator and string decoder
Problem 1: Arithmetic Expression Evaluator
Implement an arithmetic expression evaluator that processes expressions from a text file, with one expression per line. For each line, the system should output the evaluated result.
The evaluator must support:
- Integers
- Standard arithmetic operators: addition (
+), subtraction (-), multiplication (*), division (/) - Parentheses for grouping expressions
- Correct operator precedence
- Whitespace within expressions
Candidates must describe how to handle the following edge cases and constraints:
- Invalid tokens encountered in an expression
- Divide-by-zero errors
- Integer overflow scenarios
- Expressions that are very long (e.g., exceeding typical line buffer sizes)
Additionally, candidates should explain:
- The data structures used (e.g., two stacks, shunting-yard algorithm)
- The time and space complexity of their approach
- A streaming approach suitable for processing input files too large to fit entirely into memory
Problem 2: String Decoder
Implement a string decoder for inputs formatted as k[encoded_string], where k is a repeat count and encoded_string is the content to be repeated. The encoding can be nested.
Examples:
3[a2[c]]should decode toaccaccacc
The decoder must:
- Handle multi-digit repeat counts (e.g.,
10[a]) - Support UTF-8 characters within the
encoded_string - Gracefully handle malformed bracket sequences (e.g.,
3[aor3[a]]) - Achieve an optimal time complexity of O(n) and space complexity of O(n), where n is the length of the decoded string.
Candidates should provide:
- Iterative and/or recursive approaches
- An analysis of the time and space complexity for their chosen method(s)
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Core dilemma
Demonstrating robust algorithmic design for parsing and evaluation, coupled with meticulous error handling, performance optimization (especially for large inputs), and handling complex nested structures. It tests a candidate's ability to apply fundamental data structures and algorithms to practical, real-world parsing problems, while also considering system-level constraints like memory and file I/O.
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Solve expression evaluator and string decoder
Problem 1: Arithmetic Expression Evaluator
Implement an arithmetic expression evaluator that processes expressions from a text file, with one expression per line. For each line, the system should output the evaluated result.
The evaluator must support:
- Integers
- Standard arithmetic operators: addition (
+), subtraction (-), multiplication (*), division (/) - Parentheses for grouping expressions
- Correct operator precedence
- Whitespace within expressions
Candidates must describe how to handle the following edge cases and constraints:
- Invalid tokens encountered in an expression
- Divide-by-zero errors
- Integer overflow scenarios
- Expressions that are very long (e.g., exceeding typical line buffer sizes)
Additionally, candidates should explain:
- The data structures used (e.g., two stacks, shunting-yard algorithm)
- The time and space complexity of their approach
- A streaming approach suitable for processing input files too large to fit entirely into memory
Problem 2: String Decoder
Implement a string decoder for inputs formatted as k[encoded_string], where k is a repeat count and encoded_string is the content to be repeated. The encoding can be nested.
Examples:
3[a2[c]]should decode toaccaccacc
The decoder must:
- Handle multi-digit repeat counts (e.g.,
10[a]) - Support UTF-8 characters within the
encoded_string - Gracefully handle malformed bracket sequences (e.g.,
3[aor3[a]]) - Achieve an optimal time complexity of O(n) and space complexity of O(n), where n is the length of the decoded string.
Candidates should provide:
- Iterative and/or recursive approaches
- An analysis of the time and space complexity for their chosen method(s)