EXPTREE codechef problem not able to understand the proof , please help !!

Revision en1, by shahianshu, 2018-10-22 19:19:51

Hello,

EXPTREE Problem link

i was reading the editorial for Exptree i was not able to understand the proof mentioned by @gil_vegliach in the commments, as he mentioned that for any two vertices v1 and v2 in [1..n] in tree T1 , T2 resp., if we remove (parent[v1],v1) and (parent[v2],v2) will lead to same tree only if T1 = T2 initially but i came up with a counter example of 7 nodes

(T1)                                           (T2)
0                  and                           0
/   \                                            /   \
0      0                                          0     0
/         \                                                \
( 0 )            0                                                 0
/   \                                             /  \
0     0                                            0    0
\
( 0 )

v1 is the vertex marked with () in T1 and v2 is the vertex marked with () in T2 , now if i remove the edge between v1 and it's parent , and remove the edge between v2 and it's parent then i get the same tree but T1 != T2. Now i am not able to understand wheather the proof is wrong or i have understood it incorrectly

#### History

Revisions

Rev. Lang. By When Δ Comment
en1 shahianshu 2018-10-22 19:19:51 1710 Initial revision (published)