spoj#PAIRSUM. Sum of Pairwise Products
Sum of Pairwise Products
Given N non negative numbers, the task is to answer M queries.
Each query is as follows:
Given u,v you need to find the pairwise product sum (u and v are zero indexed)
auau + au+1au+1 + au+1au + au+2au+2 + au+2au+1 + au+2au + ... + avav + avav-1 + ... + avau
Input
N a0 a1 ... aN-1 M u1 v1 u2 v2 ... uM vM
Output
Print the answer for each query in a separate line.
Example
Input: 5 2 0 1 3 3 3 0 2 1 2 3 4</p>Output: 7 1 27
Constraints
0 <= u <= v < N
N <= 100000
M <= 100000
0 <= ai <= 1000000