2346. Largest 3 Same Digit Number In String¶

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2346. 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.

Solution¶

class Solution {
    public String largestGoodInteger(String s) {
        int n = s.length();
        String res = ""; 
        boolean found = false;
        for (int i = 0; i < n - 2; i++) {
            if (s.charAt(i) == s.charAt(i + 1) && s.charAt(i + 1) == s.charAt(i + 2)) {
                String current = s.charAt(i) + "" + s.charAt(i + 1) + ""+ s.charAt(i + 2);
                if (current.compareTo(res) > 0) {
                    res = current;
                } 
            }
        }
        return res;
    }
}

Complexity Analysis¶

• Time Complexity: O(?)
• Space Complexity: O(?)

Approach¶

Detailed explanation of the approach will be added here