Q37,paper 3,d13. The longest common subsequence of the sequences X = and Y = has length

(A) 2

 (B) 3

(C) 4

 (D)5

^{Answer C.}

^Explanation 

^{let a string}   ACT T GCG

ACT,AT T C,T,ACT TGC

are all subsequences.

Whereas T T A

is not a subequence

A common subequence of two strings is a subsequence that appears in

both strings. A longest common subsequence is a common subsequence

of maximum length. In our case

X=<A, B, C, B, D, A,

Y = <B, D, C, A, B, A>

X= BCBXA

Y=BXCXBA

String BCBA is the common longest subsequence.