Longest Consecutive Sequence

LongestConsecutive.cs

int[] nums = {1,6,10,4,7,9,12,11,5,13};
int max = nums.Max ( );

int[] vals = new int[max+1];

for(int i = 0;i<nums.Length;i++)
	vals[nums[i]]++;
Dictionary<int,int> lengthMap = new Dictionary<int,int>();
int k=0;
for(k=1;k<vals.Length;k++)
{
	if(vals[k-1]==0 && vals[k]==1)//from nothing to something (getting up on the plataeu)
		lengthMap.Add(k,1);
	if(vals[k]==0 && vals[k-1]==1)//from something to nothing (getting down off the plataeu)
		lengthMap[lengthMap.Last ().Key]=k;//marking the end of  a sequence		
}
//if there are all "ones" towards the end. 
if(k==vals.Length && vals[k-1]==1)
	lengthMap[lengthMap.Last ().Key]=k;
	
//This sorting is not required. 
//We can keep the differences in a third element 
//and thus maintain a list of tuples where the last element is the difference 
//Now finding the maximum difference is the longest sequence
KeyValuePair<int,int> longestSeqStartEnd = lengthMap.OrderByDescending (m => m.Value - m.Key).First ();

Console.WriteLine("The longest sequence is ");

for( int i = longestSeqStartEnd.Key;i<longestSeqStartEnd.Value;i++)
	Console.WriteLine(i);