Leetcode 1202 - smallest string - union find algorithm - weekly contest 155

1202_smallString_unionFind.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace unionFind
{
    class Program
    {
        static void Main(string[] args)
        {
        }

        public string SmallestStringWithSwaps(string s, IList<IList<int>> pairs)
        {
            var length = s.Length; 
            var parent = new int[length];
            for (int i = 0; i < length; i++)
                parent[i] = i; 

            foreach(var pair in pairs)
            {
                var first = pair[0];
                var second = pair[1];

                if(parent[first] != parent[second])
                {
                    // union two set; 
                    union(parent, parent[first], parent[second]);
                }
            }


        }

        private static void union(int[] parent, int first, int second)
        {
            int iterate = first;
            var newParent = parent[second];

            while (iterate != newParent)
            {
                var tmp = parent[iterate];
                parent[iterate] = newParent;
                iterate = tmp;                
            }
        }
    }
}