Largest Number solution and explanation

from typing import List

def largestNumber(nums: List[int]) -> str:
    num_strs = list(map(str, nums))
    num_strs.sort(key=lambda x: x*10, reverse=True)
    if num_strs[0] == '0':
        return '0'
    return ''.join(num_strs)

if __name__ == "__main__":
    print(largestNumber([3, 30, 34, 5, 9]))

import java.util.Arrays;

public class LargestNumber {
    public String largestNumber(int[] nums) {
        String[] numStrs = new String[nums.length];
        for (int i = 0; i < nums.length; i++) {
            numStrs[i] = String.valueOf(nums[i]);
        }
        Arrays.sort(numStrs, (a, b) -> (b + a).compareTo(a + b));
        if (numStrs[0].equals("0")) {
            return "0";
        }
        StringBuilder result = new StringBuilder();
        for (String numStr : numStrs) {
            result.append(numStr);
        }
        return result.toString();
    }

    public static void main(String[] args) {
        LargestNumber ln = new LargestNumber();
        int[] nums = {3, 30, 34, 5, 9};
        System.out.println(ln.largestNumber(nums));
    }
}

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>

using namespace std;

string largestNumber(vector<int>& nums) {
    vector<string> numStrs;
    for (int num : nums) {
        numStrs.push_back(to_string(num));
    }
    sort(numStrs.begin(), numStrs.end(), [](const string& a, const string& b) {
        return a + b > b + a;
    });
    if (numStrs[0] == "0") {
        return "0";
    }
    string result;
    for (const string& numStr : numStrs) {
        result += numStr;
    }
    return result;
}

int main() {
    vector<int> nums = {3, 30, 34, 5, 9};
    cout << largestNumber(nums) << endl;
    return 0;
}

function largestNumber(nums) {
    nums.sort((a, b) => ('' + b + a) - ('' + a + b));
    if (nums[0] === 0) return '0';
    return nums.join('');
}

console.log(largestNumber([3, 30, 34, 5, 9]));

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int compare(const void *a, const void *b) {
    char *num1 = *(char **)a;
    char *num2 = *(char **)b;
    char option1[20], option2[20];
    sprintf(option1, "%s%s", num1, num2);
    sprintf(option2, "%s%s", num2, num1);
    return strcmp(option2, option1);
}

char* largestNumber(int* nums, int numsSize) {
    char* numsStr[numsSize];
    for (int i = 0; i < numsSize; i++) {
        numsStr[i] = malloc(11);
        sprintf(numsStr[i], "%d", nums[i]);
    }
    qsort(numsStr, numsSize, sizeof(char*), compare);
    if (numsStr[0][0] == '0') {
        return "0";
    }
    int totalLength = 0;
    for (int i = 0; i < numsSize; i++) {
        totalLength += strlen(numsStr[i]);
    }
    char* result = malloc(totalLength + 1);
    result[0] = '\0';
    for (int i = 0; i < numsSize; i++) {
        strcat(result, numsStr[i]);
        free(numsStr[i]);
    }
    return result;
}

int main() {
    int nums[] = {3, 30, 34, 5, 9};
    int size = sizeof(nums) / sizeof(nums[0]);
    char* result = largestNumber(nums, size);
    printf("%s\n", result);
    free(result);
    return 0;
}

using System;
using System.Collections.Generic;
using System.Linq;

public class Solution {
    public string LargestNumber(int[] nums) {
        var numStrs = nums.Select(num => num.ToString()).ToArray();
        Array.Sort(numStrs, (a, b) => string.Compare(b + a, a + b));
        if (numStrs[0] == "0") {
            return "0";
        }
        return string.Concat(numStrs);
    }

    public static void Main(string[] args) {
        Solution sol = new Solution();
        Console.WriteLine(sol.LargestNumber(new int[] {3, 30, 34, 5, 9}));
    }
}

import heapq

def largestNumber(nums):
    if not nums:
        return ''
    nums_str = list(map(str, nums))
    heap = [(-1 * int(num * 10), num) for num in nums_str]
    heapq.heapify(heap)
    if heap[0][1] == '0':
        return '0'
    result = ''
    while heap:
        result += heapq.heappop(heap)[1]
    return result

print(largestNumber([3, 30, 34, 5, 9]))

function largestNumber(nums: number[]): string {
    nums.sort((a, b) => {
        const [ab, ba] = [String(a) + String(b), String(b) + String(a)];
        return +ba - +ab;
    });

    return nums[0] ? nums.join('') : '0';
}

func largestNumber(nums []int) string {
	vs := make([]string, len(nums))
	for i, v := range nums {
		vs[i] = strconv.Itoa(v)
	}
	sort.Slice(vs, func(i, j int) bool {
		return vs[i]+vs[j] > vs[j]+vs[i]
	})
	if vs[0] == "0" {
		return "0"
	}
	return strings.Join(vs, "")
}