The largest 3 same digits in the string of leetcode simple question

subject

Give you a string num , Represents a large integer . If an integer satisfies all of the following conditions , The integer is considered to be a High quality integer ：

The integer is num One length of the is 3 Of Substring .
The integer is repeated by a unique number 3 Secondary composition .
Returns... As a string The largest good integer . If there is no integer that meets the requirements , Then return an empty string “” .

Be careful ：

Substring Is a sequence of consecutive characters in a string .
num Or high-quality integers may exist Leading zero .

Example 1：

Input ：num = “6777133339”
Output ：“777”
explain ：num There are two high-quality integers in ：“777” and “333” .
“777” It's the biggest one , So back “777” .
Example 2：

Input ：num = “2300019”
Output ：“000”
explain ：“000” Is the only good integer .
Example 3：

Input ：num = “42352338”
Output ：“”
explain ： There is no length of 3 An integer consisting of only one unique number . therefore , There are no good integers .

Tips ：

3 <= num.length <= 1000
num Just numbers （0 - 9） form

source ： Power button （LeetCode）

Their thinking

   This problem only needs to be done with a length of 3 And then traverse the entire string , Find the largest number that meets the conditions .

class Solution:
    def largestGoodInteger(self, num: str) -> str:
        MIN=''
        for i in range(0,len(num)-2):
            if num[i]==num[i+1] and num[i+1]==num[i+2]:
                if MIN=='':
                    MIN=num[i]*3
                else:
                    MIN=num[i]*3 if int(num[i]*3)>int(MIN) else MIN
        return MIN