/// <summary>
/// assume that maximum number of cities is 50
/// Map new road as integer quickly.
/// using SortedDictionary
/// https://github.com/jianminchen/Leetcode_Julia/blob/master/source%20code/23%20Merge%20K%20sorted%20lists%20-%20using%20minimum%20heap.cs
/// </summary>
/// <param name="noCities"></param>
/// <param name="existingRoads"></param>
/// <param name="newRoads"></param>
/// <param name="roadWithCost"></param>
/// <returns></returns>
public static int getMinimumCost(
int noCities,
List <int[]> existingRoads,
int newRoads,
List <int[]> roadWithCost)
{
var quickUnion = new QuickUnion(noCities);
foreach (var item in existingRoads)
{
// adjust the value of id from 0 to N - 1
quickUnion.Union(item[0] - 1, item[1] - 1);
}
int count = quickUnion.GetCount();
var newRoadMap = new SortedDictionary <int, Queue <int[]> >();
foreach (int[] item in roadWithCost)
{
var id1 = item[0] - 1;
var id2 = item[1] - 1;
var roadCost = item[2];
if (!newRoadMap.ContainsKey(roadCost))
{
newRoadMap.Add(roadCost, new Queue <int[]>());
}
newRoadMap[roadCost].Enqueue(new int[] { id1, id2 });
}
var totalCost = 0;
while (newRoadMap.Count > 0)
{
int minCost = newRoadMap.First().Key;
var ids = newRoadMap[minCost].Dequeue();
if (newRoadMap[minCost].Count == 0)
{
newRoadMap.Remove(minCost);
}
var id1 = ids[0];
var id2 = ids[1];
var connected = quickUnion.Connected(id1, id2);
if (connected)
{
continue;
}
totalCost += minCost;
quickUnion.Union(id1, id2); // Union, not Connected
if (quickUnion.GetCount() == 1)
{
break;
}
}
if (quickUnion.GetCount() > 1)
{
return(-1);
}
return(totalCost);
}
/// <summary>
/// assume that maximum number of cities is 50
/// Map new road as integer quickly.
/// </summary>
/// <param name="noCities"></param>
/// <param name="existingRoads"></param>
/// <param name="newRoads"></param>
/// <param name="roadWithCost"></param>
/// <returns></returns>
public static int getMinimumCost(
int noCities,
List <int[]> existingRoads,
int newRoads,
List <int[]> roadWithCost)
{
var quickUnion = new QuickUnion(noCities);
foreach (var item in existingRoads)
{
// adjust the value of id from 0 to N - 1
quickUnion.Union(item[0] - 1, item[1] - 1);
}
int count = quickUnion.GetCount();
var newRoadMap = new Dictionary <int, List <int> >();
foreach (int[] item in roadWithCost)
{
var id1 = item[0] - 1;
var id2 = item[1] - 1;
var roadCost = item[2];
var newId = id1 * 50 + id2;
if (!newRoadMap.ContainsKey(roadCost))
{
newRoadMap.Add(roadCost, new List <int>());
}
newRoadMap[roadCost].Add(newId);
}
var costs = newRoadMap.Keys.ToArray();
Array.Sort(costs);
var length = costs.Length;
var totalCost = 0;
for (int i = 0; i < length; i++)
{
var current = costs[i];
var ids = newRoadMap[current];
foreach (var id in ids)
{
var id1 = id % 50;
var id2 = id / 50;
var connected = quickUnion.Connected(id1, id2);
if (connected)
{
continue;
}
totalCost += current;
quickUnion.Union(id1, id2); // Union, not Connected
}
}
if (quickUnion.GetCount() > 1)
{
return(-1);
}
return(totalCost);
}