[LeetCode 2264] Largest 3-Same-Digit Number in String

문제 바로가기

Description

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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

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• 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

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• Input: num = “2300019”
• Output: “000”
• Explanation: “000” is the only good integer.

Example 3

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

Constraints

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

Hint

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Hint 1

  We can sequentially check if “999”, “888”, “777”, … , “000” exists in num in that order. The first to be found is the maximum good integer.
	

Hint 2

  If we cannot find any of the above integers, we return an empty string “”.
	

Code

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내 제출

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class Solution {
    public String largestGoodInteger(String num) {
        for (int i = 9; i >= 0; i--) {
            String s = String.valueOf(i).repeat(3);
            if (num.contains(s)) {
                return s;
            }
        }
        return "";
    }
}

Runtime	Memory
1 ms	41.9 MB

다른 풀이

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class Solution {
    public String largestGoodInteger(String num) {
        String[] toFind = new String[]{"999", "888", "777", "666", "555", "444", "333", "222", "111", "000"};
        for (String ans : toFind) {
            if (num.contains(ans)) return ans;
        }
        return "";
    }
}

Reference

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• https://github.com/doocs/leetcode/blob/main/solution/2200-2299/2264.Largest%203-Same-Digit%20Number%20in%20String/Solution.java