1277. Largest Multiple of Three

My accepted Python solution to LeetCode problem 1277, Largest Multiple of Three, running in 18ms.

Hard

Python

Runtime 18ms

Memory 18.6MB

The problem statement is LeetCode’s and stays on their site. What follows is my accepted solution.

Python

Accepted on LeetCode — runtime 18ms, memory 18.6MB, accepted 2025-12-29.

python

class Solution:
    def largestMultipleOfThree(self, digits: List[int]) -> str:
        # Sort digits in descending order
        digits.sort(reverse=True)
        
        # If all zeros, return "0"
        if digits[0] == 0:
            return "0"
        
        # Group digits by remainder when divided by 3
        remainder = [[], [], []]
        total = 0
        for d in digits:
            remainder[d % 3].append(d)
            total += d
        
        # If total % 3 == 0, we can use all digits
        if total % 3 == 0:
            return ''.join(map(str, digits))
        
        # If total % 3 == 1, remove one digit with remainder 1 or two digits with remainder 2
        if total % 3 == 1:
            if remainder[1]:
                remainder[1].pop()
            elif len(remainder[2]) >= 2:
                remainder[2].pop()
                remainder[2].pop()
            else:
                return ""
        # If total % 3 == 2, remove one digit with remainder 2 or two digits with remainder 1
        else:
            if remainder[2]:
                remainder[2].pop()
            elif len(remainder[1]) >= 2:
                remainder[1].pop()
                remainder[1].pop()
            else:
                return ""
        
        # Combine all remaining digits and sort in descending order
        result = remainder[0] + remainder[1] + remainder[2]
        result.sort(reverse=True)
        
        if not result:
            return ""
        if result[0] == 0:
            return "0"
        
        return ''.join(map(str, result))

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Source#

Python

Source