179. Largest Number

Problem Link

Description

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Given a list of non-negative integers nums, arrange them such that they form the largest number and return it.

Since the result may be very large, so you need to return a string instead of an integer.

 

Example 1:

Input: nums = [10,2]
Output: "210"

Example 2:

Input: nums = [3,30,34,5,9]
Output: "9534330"

 

Constraints:

• 1 <= nums.length <= 100
• 0 <= nums[i] <= 109

Solution

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Python3

class Solution:
    def largestNumber(self, nums: List[int]) -> str:
        if not any(nums):
            return "0"
            
        def compare(a, b):
            if a + b > b + a:
                return -1  # a should come before b
            elif a + b < b + a:
                return 1   # b should come before a
            else:
                return 0   # a and b are equal
 
        s = list(map(str, nums))
        s.sort(key = cmp_to_key(compare))
        return "".join(s)

Python

import functools 
 
class Solution:
    def largestNumber(self, nums):
        compare = lambda a, b: 1 if a+b > b+a else -1 if a+b < b+a else 0
        _nums = list(map(str, nums))
        _nums.sort(key=functools.cmp_to_key(compare), reverse=True)
        return str(int(''.join(_nums)))