It tracks k smallest sequences which has length less then k.

```
public bool IncreasingTriplet(int[] nums)
{
int k = 3;
if(nums == null || nums.Length < k) return false;
int[] seq = new int[k];
for(int i = 0; i < k; i++) seq[i] = int.MaxValue;
foreach(int aNum in nums)
{
for(int j = 0; j < seq.Length; j++)
{
if(aNum <= seq[j])
{
seq[j] = aNum;
if(j == seq.Length - 1) return true;
else break;
}
}
}
return false;
}
```