#1184 - Distance Between Bus Stops

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Problem Description

A bus has n stops numbered from 0 to n - 1 that form a circle. We know the distance between all pairs of neighboring stops where distance[i] is the distance between the stops number i and (i + 1) % n.

The bus goes along both directions i.e. clockwise and counterclockwise.

Return the shortest distance between the given start and destination stops.

Solution

/**
 * @param {number[]} distance
 * @param {number} start
 * @param {number} destination
 * @return {number}
 */
var distanceBetweenBusStops = function(distance, start, destination) {
  const normalizeIndices = (from, to) => from < to ? [from, to] : [to, from];

  const [left, right] = normalizeIndices(start, destination);
  const clockwiseDistance = distance.slice(left, right).reduce((sum, dist) => sum + dist, 0);
  const totalDistance = distance.reduce((sum, dist) => sum + dist, 0);
  const counterclockwiseDistance = totalDistance - clockwiseDistance;

  return Math.min(clockwiseDistance, counterclockwiseDistance);
};