Match the pairs in the following questions by writing the corresponding letters only.
(A) - S Catalyn no http://gatecse.in/wiki/Number_of_Binary_trees_possible_with_n_nodes
(B) - R. Choosing n locations out of 2n to place 0. Remaining automatically become 1.
(C) -P An even permutation is a permutation obtainable from an even number of two-element swaps, For a set of elements and , there are even permutations. Ref -> http://mathworld.wolfram.com/EvenPermutation.html
(D) -> Q
Length = 6n, as it is palindrome, we need to only consider half part.
Total Length to consider 3n (Remaining 3n will be revese of this 3n)
now Choosing n 0's out of 3n. So Q is correct for D.
Let's say |c| = 5 and |p| = ...