#2264

Largest 3-Same-Digit Number in String

newbie · 255 · lc easy +19 · verified · 72.7% accepted · 1,389 likes · top 82%

Description

You are given a string num representing a large integer. An integer is "good" if it is a length-3 substring of num made entirely of one repeated digit.

Return the largest good integer as a string, or an empty string "" if no good integer exists.

Note:

- A substring is contiguous.

- Leading zeros in num or in a good integer are permitted.

Example 1:

Input: num = "6777133339"
Output: "777"
Explanation: There are two distinct good integers: "777" and "333".
"777" is the largest, so we return "777".

Example 2:

Input: num = "2300019"
Output: "000"
Explanation: "000" is the only good integer.

Example 3:

Input: num = "42352338"
Output: ""
Explanation: No substring of length 3 consists of only one unique digit. Therefore, there are no good integers.

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