hiho! is a serial contests we developed to help programmers improve their skills following some architecture. Tree, as a data structure, has a significant feature that the problem on a tree usually can be divided in to several sub-problems on sub-trees which is very similar to what we have learned in "Dynamic Programming".
The modify operation is only related to single position of the array, but segment-tree can handle more complicated operation! Let's see how Hi and Ho use the power of segment-tree!