arrays - How can we assure that a Bitonic sequence will be formed from one longest increasing subsequence and one longest decreasing subsequence? -
for example have array[]={1,3,2,7,4,6,8,9}
.
longest increasing subsequence of array[]={1,3,4,6,8,9}
, length=6.
longest decreasing subsequence of array[]={3,2}
, length=2.
then bitonic subsequence of array[]={1,3,4,6,8,9}
? if yes length=6.but length of bitonic subsequence =length of lis + length of lds -1, here not equal.
if no how can prove length of bitonic subsequence=length of lis+length of lds-1
correct me if wrong. thank you.
the formula correct , gives out 6 only... consider lis[](as lis array) , lds[] (as lds array).. when iterate left right reach position lis[index]=6 i.e. lis till array[7] 6.. lds[index=7] 1 (trivially 1 element maximum length of series)... lis[7]+lds[7]-1=(6+1-1)
now proof wanted bitonic sequence... lis[i],lds[i] represents longest increasing / decreasing sequence till i! now, want maximise that's why search on sample space! answer maximum of (lis[i]+lds[i]-1) 0<=i<=n-1 ... that -1 due repeated inclusion of element @ th position!
Comments
Post a Comment