Challenging Point72 Software Engineer Interview: Tackling Dynamic Arrays

Software Engineering
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point72 | Software Engineer | Interview Experience

Interview Date: Not specified
Result: Not specified
Difficulty: Not specified

Interview Process

The interview consisted of two main design questions that required the candidate to think critically and write code on the spot.

Technical Questions

  1. SmartString Class Template

    • Design a SmartString class template that:
      • Accepts a size_t template argument called STORAGE_SIZE with a default value of 16.
      • Supports SmartString().
      • Supports SmartString(const char* s, size_t len).
      • Implements c_str() to return a null-terminated const char*.
      • Implements length() to return the length of the string in constant time.
      • Implements max_size() to return STORAGE_SIZE - 1.
      • Ensures that const char* s does not contain \0.
    • Follow-up: Modify SmartString to allow storing more characters than STORAGE_SIZE.

  2. Expandable Array Class Template

    • Design a fast, expandable Array<T> class template with the following requirements:
      • Stable addresses: once allocated, an element’s address never changes until the array is destroyed.
      • Non-contiguous growth: elements can be stored in separate blocks; supports dynamic expansion.
      • Type requirement: T must be “0-initializable”.
      • On-demand creation: accessing a missing element allocates and zero-initializes it automatically.
      • Direct access: fast random access by index.
    • Implement T& at(size_t index); which will auto-create the element if not already done.
    • Part 2: Ensure that concurrent at() calls for the same index return a reference to the same memory location.

Tips & Insights

Both questions required a strong understanding of data structures and the ability to think creatively. Candidates should be prepared to write code and explain their thought process clearly.