1432. Max Difference You Can Get From Changing an Integer

Description

You are given an integer num. You will apply the following steps exactly two times:

• Pick a digit x (0 <= x <= 9).
• Pick another digit y (0 <= y <= 9). The digit y can be equal to x.
• Replace all the occurrences of x in the decimal representation of num by y.
• The new integer cannot have any leading zeros, also the new integer cannot be 0.

Let a and b be the results of applying the operations to num the first and second times, respectively.

Return the max difference between a and b.

 

Example 1:

Input: num = 555
Output: 888
Explanation: The first time pick x = 5 and y = 9 and store the new integer in a.
The second time pick x = 5 and y = 1 and store the new integer in b.
We have now a = 999 and b = 111 and max difference = 888

Example 2:

Input: num = 9
Output: 8
Explanation: The first time pick x = 9 and y = 9 and store the new integer in a.
The second time pick x = 9 and y = 1 and store the new integer in b.
We have now a = 9 and b = 1 and max difference = 8

 

Constraints:

• 1 <= num <= 10⁸

 

Solutions

Solution: Greedy

• Time complexity: O(n)
• Space complexity: O(n)

 

JavaScript

/**
 * @param {number} num
 * @return {number}
 */
const maxDiff = function (num) {
  const numStringify = `${num}`;
  let max = (min = numStringify);

  for (let index = 0; index < numStringify; index++) {
    const value = numStringify[index];

    if (value !== '9') {
      max = max.replaceAll(value, '9');
      break;
    }
  }
  for (let index = 0; index < numStringify; index++) {
    const value = numStringify[index];

    if (index === 0) {
      if (value !== '1') {
        min = min.replaceAll(value, '1');
        break;
      }
      continue;
    }
    if (value === '0' || value === numStringify[0]) continue;
    min = min.replaceAll(value, '0');
    break;
  }
  return max - min;
};