Search⌘ K
AI Features
Home
Courses
Grokking the Coding Interview Patterns in JavaScript

Solution: Freedom Trail

Explore the dynamic programming approach to solve the Freedom Trail problem where you spell out a keyword by rotating a circular ring. This lesson guides you through memoization and optimal steps calculation, helping you minimize total rotations and button presses efficiently.

We'll cover the following...

Statement

You are given a circular ring represented by a string ring, and a keyword represented by a string key that you need to spell out.

Initially, the first character of ring (index 00) is aligned at the "12:00" position. To spell each character in key sequentially, you must:

  1. Rotate the ring clockwise or anticlockwise. Each rotation by one position counts as one step. Rotate until a character in ring that matches the current target character key[i] is aligned at the "12:00" position.

  2. Press the center button to confirm the character, which counts as one additional step.

After pressing, you move on to spell the next character in key. The ring is circular, meaning its last character wraps around to its first character.

Return the minimum total number of steps required to spell all characters in key.

Note: Each button press counts as one step in addition to the rotation steps.

Constraints:

  • ...