Thanks @admin. below ans is just C# version of @qgambit2 's one

```
public class Solution {
public bool IncreasingTriplet(int[] nums) {
int a = int.MaxValue;
int b = int.MaxValue;
for (int i = 0; i < nums.Length; i++) {
if (nums[i] <= a) a = nums[i];
else if (nums[i] <= b) b = nums[i];
else return true;
}
return false;
}
}
```