maximize-distance-to-closest-person.js

/**
 * Maximize Distance to Closest Person
 *
 * In a row of seats, 1 represents a person sitting in that seat, and 0 represents that the seat is empty.
 *
 * There is at least one empty seat, and at least one person sitting.
 *
 * Alex wants to sit in the seat such that the distance between him and the closest person to him is maximized.
 *
 * Return that maximum distance to closest person.
 *
 * Example 1:
 *
 * Input: [1,0,0,0,1,0,1]
 * Output: 2
 * Explanation:
 * If Alex sits in the second open seat (seats[2]), then the closest person has distance 2.
 * If Alex sits in any other open seat, the closest person has distance 1.
 * Thus, the maximum distance to the closest person is 2.
 *
 * Example 2:
 *
 * Input: [1,0,0,0]
 * Output: 3
 * Explanation:
 * If Alex sits in the last seat, the closest person is 3 seats away.
 * This is the maximum distance possible, so the answer is 3.
 *
 * Note:
 *
 * - 1 <= seats.length <= 20000
 * - seats contains only 0s or 1s, at least one 0, and at least one 1.
 */

/**
 * @param {number[]} seats
 * @return {number}
 */
const maxDistToClosest = seats => {
  const n = seats.length;
  let max = -Infinity;

  for (let i = 0, j = 0; i < n; i = j) {
    // locate the left border of 0 [i]
    for (i = j; i < n && seats[i] === 1; i++) {}

    // locate the right border of 0 [j-1]
    for (j = i; j < n && seats[j] === 0; j++) {}

    if (i === 0 || j === n) {
      max = Math.max(max, j - i);
    } else {
      max = Math.max(max, Math.floor((j - i + 1) / 2));
    }
  }

  return max;
};

export { maxDistToClosest };