1769-minimum-number-of-operations-to-move-all-balls-to-each-box.js

/**
 * @param {string} boxes
 * @return {number[]}
 */
const minOperations = function(boxes) {
  const n = boxes.length
  const res = Array(n).fill(0)
  let cum = 0, sum = 0
  for(let i = 0; i < n; i++) {
    res[i] += sum
    cum += +boxes[i]
    sum += cum
  }
  cum = 0, sum = 0
  for(let i = n - 1; i >= 0; i--) {
    res[i] += sum
    cum += +boxes[i]
    sum += cum
  }
  return res
};


// another


/**
 * @param {string} boxes
 * @return {number[]}
 */
const minOperations = function(boxes) {
  const res = []
  for(let i = 0, len = boxes.length; i < len; i++) {
    res[i] = helper(boxes, i)
  }

  return res
};

function helper(str, idx) {
  let res = 0
  for(let i = 0, len = str.length; i < len; i++) {
    if(i === idx || str[i] === '0') continue
    res += Math.abs(i - idx)
  }
  return res
}

// another

/**
 * @param {string} boxes
 * @return {number[]}
 */
 const minOperations = function(boxes) {
  const n = boxes.length
  const res = Array(n).fill(0)
  let cnt = 0, sum = 0
  for(let i = 0; i < n; i++) {
    res[i] = sum
    cnt += boxes[i] === '1' ? 1 : 0
    sum += cnt
  }
  cnt = 0, sum = 0
  for(let i = n - 1; i >= 0; i--) {
    res[i] += sum
    cnt += boxes[i] === '1' ? 1 : 0
    sum += cnt
  }
  return res
};