Step 1: Start with root node (t = 1)
Step 2: Search for a split s* among the set if all
possible candidates s that gives the purest
decrease in impurity.
Step 3: Split node 1 (t = 1) into two nodes (t = 2, t = 3)
using the split s*.
Step 4: Repeat the split search process (t = 2, t = 3) as
indicated in steps 1-3 until the tree growing the
tree growing rules are met.