#2515 - Shortest Distance to Target String in a Circular Array

Problem Description

You are given a 0-indexed circular string array words and a string target. A circular array means that the array's end connects to the array's beginning.

Formally, the next element of words[i] is words[(i + 1) % n] and the previous element of words[i] is words[(i - 1 + n) % n], where n is the length of words.

Starting from startIndex, you can move to either the next word or the previous word with 1 step at a time.

Return the shortest distance needed to reach the string target. If the string target does not exist in words, return -1.

Solution

/**
 * @param {string[]} words
 * @param {string} target
 * @param {number} startIndex
 * @return {number}
 */
var closestTarget = function(words, target, startIndex) {
  const n = words.length;
  let minDistance = Infinity;

  for (let i = 0; i < n; i++) {
    if (words[i] === target) {
      const forward = Math.abs(i - startIndex);
      const backward = n - forward;
      minDistance = Math.min(minDistance, forward, backward);
    }
  }

  return minDistance === Infinity ? -1 : minDistance;
};