#670 - Maximum Swap

Medium • View on LeetCode • View on GitHub

Problem Description

You are given an integer num. You can swap two digits at most once to get the maximum valued number.

Return the maximum valued number you can get.

Solution

/**
 * @param {number} num
 * @return {number}
 */
var maximumSwap = function(num) {
  const digits = [...(num).toString()];
  const last = new Array(10).fill(-1);
  digits.forEach((d, i) => last[d] = i);

  for (let i = 0; i < digits.length; i++) {
    for (let d = 9; d > digits[i]; d--) {
      if (last[d] > i) {
        [digits[i], digits[last[d]]] = [digits[last[d]], digits[i]];
        return +digits.join('');
      }
    }
  }

  return num;
};