2264

2264. Largest 3-Same-Digit Number in String (Easy)

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.

Companies: opentext, PayPay

Related Topics:
String

Similar Questions:

• Largest Odd Number in String (Easy)

Solution 1.

// OJ: https://leetcode.com/problems/largest-3-same-digit-number-in-string
// Author: github.com/lzl124631x
// Time: O(N)
// Space: O(1)
class Solution {
public:
    string largestGoodInteger(string s) {
        char c = 0;
        for (int i = 2; i < s.size(); ++i) {
            if (s[i] == s[i - 1] && s[i] == s[i - 2]) c = max(c, s[i]);
        }
        return c ? string(3, c) : "";
    }
};