#2264 - Largest 3-Same-Digit Number in String

Easy • View on LeetCode • View on GitHub

String

Problem Description

You are given a string num representing a large integer. An integer is good if it meets the following conditions:

It is a substring of num with length 3.
It consists of only one unique digit.

Return the maximum good integer as a string or an empty string "" if no such integer exists.

Note:

A substring is a contiguous sequence of characters within a string.
There may be leading zeroes in num or a good integer.

Solution

/**
 * @param {string} num
 * @return {string}
 */
var largestGoodInteger = function(num) {
  let result = '';

  for (let i = 0; i <= num.length - 3; i++) {
    const substring = num.slice(i, i + 3);
    if (substring[0] === substring[1] && substring[1] === substring[2]) {
      if (substring > result) {
        result = substring;
      }
    }
  }

  return result;
};