NITK06 - MODIFY SEQUENCE
Suppose we have a sequence of non-negative integers, Namely a1, a2, ..., an. At each time we can choose one term ai with 0 < i < n and we subtract 1 from both ai and ai+1. We wonder whether we can get a sequence of all zeros after several operations.
The first line is the number of test cases T (0 < T <= 20).
The first line of each test case is a number N (0 < N <= 10000). The next line is N non-negative integers, 0 <= ai <= 109.
If it can be modified into all zeros with several operations output “YES” in a single line, otherwise output “NO” instead.
Input: 2 2 1 2 2 2 2 Output: NO YES
It is clear that [1 2] can be reduced to [0 1] but no further to convert all integers to 0. Hence, the output is NO.
In second case, output is YES as [2 2] can be reduced to [1 1] and then to [0 0] in just two steps.
easy one...need to observe pattern thats it :)
nice adhoc ques.
easy and nice..there should be more such probs on spoj..