README.md

2264. Largest 3-Same-Digit Number in String

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.

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.

Constraints:

• 3 <= num.length <= 1000
• num only consists of digits.

Solutions (Rust)

1. Solution

impl Solution {
    pub fn largest_good_integer(num: String) -> String {
        let num = num.into_bytes();
        let goods = num.windows(3).filter(|n| n[0] == n[1] && n[1] == n[2]);
        let largest_good = goods.max().unwrap_or(&[]);

        String::from_utf8(largest_good.to_vec()).unwrap()
    }
}