670.js

/** ------------------------------------------------------------------------------
 * 
 * 670. Maximum Swap
 * Topics: Math, Greedy
 * https://leetcode.com/problems/maximum-swap/description/?envType=daily-question&envId=2024-10-17
 * 
 ------------------------------------------------------------------------------ */
/**
 * @param {number} num
 * @return {number}
 */
var maximumSwap = function (num) {
  const digits = num.toString().split("")
  let max = -1,
    maxIdx = -1,
    leftIdx = -1,
    rightIdx = -1

  for (let i = digits.length - 1; i >= 0; i--) {
    const digit = Number(digits[i])
    console.log(digit)
    if (digit > max) {
      console.log("digit bigger than max")
      max = digit
      maxIdx = i
    } else if (digit < max) {
      console.log("digit smaller than max")
      leftIdx = i
      rightIdx = maxIdx
    }
  }

  if (leftIdx === -1) return num
  ;[digits[leftIdx], digits[rightIdx]] = [digits[rightIdx], digits[leftIdx]]
  return Number(digits.join(""))
}

const maximumSwap = (num) => {
  const nums = num.toString().split("")

  let maxIdx = nums.length - 1,
    left = -1,
    right = nums.length - 1

  for (let i = maxIdx; i >= 0; i--) {
    const current = Number(nums[i])
    const max = Number(nums[maxIdx])

    if (current > max) {
      maxIdx = i
    } else if (current < max) {
      right = maxIdx
      left = i
    }
  }

  if (left == -1) return num
  ;[nums[left], nums[right]] = [nums[right], nums[left]]

  return Number(nums.join(""))
}