Help in ZCO13001

help
#1

https://www.codechef.com/viewsolution/28055543
explain the line sum=sum+(n-(2i-1))(arr[n-i]);

#2

See the Editorial here or my solution here.

4 Likes
#3

i cant see the solution can you tell how did they open the summation formula
for solution access has been denied

#4

See here.

2 Likes