Find the minimum number of moves to make all washing machines have the same number of dresses (LeetCode)

leetcode-super-washing-machines.js

// Designed to solve this LeetCode problem: https://leetcode.com/problems/super-washing-machines/
// Author: Crates McD (https://cr8s.net)
// Runtime: 52 ms, faster than 100.00% of JavaScript online submissions for Super Washing Machines.
// Memory Usage: 35 MB, less than 100.00% of JavaScript online submissions for Super Washing Machines.
// Time complexity: O(n); space complexity: O(1)

/**
 * @param {number[]} machines
 * @return {number}
 */
const findMinMoves = (machines) => {
  const sum = machines.reduce((sum, num) => sum + num, 0);
  const avg = Math.floor(sum / machines.length);
  let ans = 0;
  let rightTotal;

  if (avg * machines.length !== sum) return -1;

  for(let i = 0, leftTotal = 0; 
    i < machines.length; 
    leftTotal += machines[i++]
  ) {
    machines[i] -= avg;
    rightTotal = -leftTotal - machines[i];
    ans = Math.max(ans, 
      Math.max(0, -leftTotal) + Math.max(0, -rightTotal)
    );
  }
  return ans;
};