Leetcode 179: Largest Number

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.

 

public class Solution {
    public class NumberComparer : IComparer<int>
    {
        public int Compare(int a, int b)
        {
            int da = 10, db = 10, t1 = a, t2 = b;
            
            while (t1 >= 10)
            {
                t1 = t1 / 10;
                da *= 10;
            }
            
            while (t2 >= 10)
            {
                t2 = t2 / 10;
                db *= 10;
            }
            
            return (b * da + a) - (a * db + b);  
        }
    }
    
    public string LargestNumber(int[] nums) {
        Array.Sort(nums, new NumberComparer());
        
        var sb = new StringBuilder();
        bool leadingZero = true;
        
        foreach (var n in nums)
        {
            if (n == 0 && leadingZero) continue;
            
            leadingZero = false;
                
            sb.Append(n);
        }
        
        if (sb.Length == 0) sb.Append(0);
        
        return sb.ToString();
    }
}