Help for this page

interval (1,20] subintervals (1,3],(5,10],(11,12],(15,17] A (sort of) balanced tree would look like: ... (1,3] (15,17] (11,12]

If you consider the number 4 with the above tree 4<=5 so you traverse down the left side. 4>1 && 4>3 so you take the right child ... 12>10 so go down right branch 12<=15 so go down left branch 12>11 and 12<=12 so 12 is covered.<