Leetcode Largest Number problem solution

def largestNumber(self, nums):
        numstr = sorted([str(num) for num in nums])
        curr = [numstr[0]]
        for i in range(1, len(nums)):
            if curr[-1] +numstr[i] > numstr[i]+curr[-1]:
                numstr[i-len(curr)] = numstr[i]
                numstr[i] = curr[-1]
            elif curr[-1] +numstr[i] == numstr[i]+curr[-1]:
                curr.append(numstr[i])
            else:
                curr = [numstr[i]]
        
        result = ''.join(reversed(numstr)) 
        if int(result)>0:
            return result
        else:
            return '0'

public class Solution {
    
    public String largestNumber(int[] nums) {
        
       	PriorityQueue<Integer> pq = new PriorityQueue<Integer>(nums.length, new Comparator<Integer>(){
			
		    public int compare(Integer a,Integer b){
			    
			    String num1 = String.valueOf(a)+String.valueOf(b);
			    String num2 = String.valueOf(b)+String.valueOf(a);
			    
			    return num2.compareTo(num1);
			}
		});

		for (int a : nums)	pq.offer(a);
		
		String res="";	
		
		while(!pq.isEmpty()) res+=pq.poll();
		
		if(res.charAt(0)=='0') return "0";
		
        return res;
    }
}

static bool comparator(string a, string b)
    {
        return (a+b) > (b+a);
    }
    string largestNumber(vector<int>& nums) {
        
        vector<string> v;
        
        for(int i = 0; i < nums.size(); i++)
            v.push_back(to_string(nums[i]));
        
        sort(v.begin(), v.end(), comparator);
        
        string s = "";
        
        for(int i = 0; i < v.size(); i++)
            s += v[i];
        
        while(s.size() > 1 && s[0] == '0')
            s.erase(s.begin());
        
        return s;
        
    }

int compare(const void* a, const void* b) {
	const char** ia = (const char*)a;
	const char** ib = (const char*)b;
	char* string1[20] = { '' };
	char* string2[20] = { '' };
	strcat(string1, *ia);
	strcat(string1, *ib);
	strcat(string2, *ib);
	strcat(string2, *ia);
	return -1*strcmp(string1, string2);
}
char * largestNumber(int* nums, int numsSize){
	char* zero = "0";
	char** temp = malloc(sizeof(char*) * numsSize);
	for (int i = 0; i < numsSize; i++) {
		temp[i] = malloc(sizeof(char) * 10);
		sprintf(temp[i], "%d", nums[i]);
	}
	qsort(temp, numsSize, sizeof(char*) , compare);

	if (!strcmp(temp[0], "0")) { return "0"; }

	char* ans = malloc(sizeof(char) * 500);
	ans[0] = '';
	for (int i = 0; i < numsSize; i++) {
		strcat(ans, temp[i]);
	}
	printf("%s", ans);
	return ans;
}