Largest Number

Description：

Given a list of non negative integers, arrange them such that they form the largest number.

For example, given [3, 30, 34, 5, 9], the largest formed number is 9534330.

Note: The result may be very large, so you need to return a string instead of an integer.

Code：

 int islesseq(int&a, int&b)
    {
        stringstream ss;
        string strA, strB;
        
        ss << a;
        ss >> strA;
        ss.clear();
        ss << b;
        ss >> strB;
        
        if (strA+strB <= strB+strA)
        {
            return 1;
        }
        else
            return 0;
    }
    
    int partition(vector<int>&nums, int low, int high)
    {
        int key = nums[low];
        while (low<high)
        {
            while (low < high && islesseq(key,nums[high]))--high;
            nums[low] = nums[high];
            while (low < high && islesseq(nums[low],key))++low;
            nums[high] = nums[low];
        }
        nums[low] = key;
        return low;
    }
    
    void sort(vector<int>&nums, int low, int high)
    {
        if (low < high)
        {
            int pivot = partition(nums,low, high);
            sort(nums,low,pivot-1);
            sort(nums, pivot+1, high);
        }
    }
    
    string largestNumber(vector<int>& nums) {
        sort(nums,0, nums.size()-1);
        if (nums[nums.size()-1] == 0)
            return "0";
        stringstream ss;
        for (int i = nums.size()-1; i >= 0; --i)
        {
            ss<<nums[i];
        }
        return ss.str();
    }