27 lines
677 B
Ruby
27 lines
677 B
Ruby
|
#Given an array replace every element by product of previous and next
|
||
|
|
#first element is replaced by product of first and second and last element by product of last and second last
|
||
|
|
#Time-complexity: O(n),Auxiliary-space: O(1)
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
def modify(a)
|
||
|
|
len=a.length
|
||
|
|
if len<=0
|
||
|
|
return -1
|
||
|
|
end
|
||
|
|
#update first element
|
||
|
|
prev=a[0]
|
||
|
|
a[0]*=a[1]
|
||
|
|
for i in 1...len-1
|
||
|
|
current=a[i] #Keep track of current element
|
||
|
|
a[i]=prev*a[i+1]
|
||
|
|
prev=current #Store current element for next iteration
|
||
|
|
end
|
||
|
|
#update last element
|
||
|
|
a[len-1]*=prev
|
||
|
|
return a
|
||
|
|
end
|
||
|
|
modify([3,6,1,7,8,2]) # => [18, 3, 42, 8, 14, 16]
|
||
|
|
|
||
|
|
|
||
|
|
|