Hi I am currently trying to solve my first problem with segment tree. Link to the problem:http://www.hackerearth.com/tracks/pledge-2015-medium/xor-in-tree-1/

I couldn't understand the segment tree implementation in context to this problem which is present in the editorial in the problem setter's solution.

What does T[i] store here?

For the second query, why

int res = path_xor[u] ^ path_xor[v] ^ ST.get_xor(pos[u]) ^ ST.get_xor(pos[v]) ^ a[c];

and not

int res = ST.get_xor(pos[u]) ^ ST.get_xor(pos[v]) ^ a[c]; for the second query?

Currently, I could only understand that the tree is first ordered so that it becomes inline ie topological sort.Now the segment tree works on this topologically sorted tree.