Rotate Left - codepath/compsci_guides GitHub Wiki

Unit 3 Session 1 (Click for link to problem statements)

U-nderstand

Understand what the interviewer is asking for by using test cases and questions about the problem.

• What if n is larger than the number of characters in the string?
  • This won't be the case, 1 <= n <= len(str).

P-lan

Plan the solution with appropriate visualizations and pseudocode.

General Idea: Slide the input string into two components and then combine them at the end.

1) Slice the second half of the string (the characters from n onward)
2) Slice the first half of the string (the characters up to n)
3) Return these two components added together in the order: second, first

I-mplement

def rotate_left(s, n):
    return s[n:] + s[:n]