Equal Cargo Split
Medium1s time · 256MB memory · arrays, prefix sums
A cargo train must be split at one wagon for weighing: everything strictly before the chosen wagon goes on the left scale, everything strictly after it on the right scale (the chosen wagon itself is on neither).
Determine whether there exists a wagon such that the sum of all values before it equals the sum of all values after it.
Input
The first line contains one integer n — the number of wagons.
The second line contains n integers a₁ … aₙ.
Output
Print YES if such a wagon exists, otherwise NO.
Constraints
- 1 ≤ n ≤ 2·10⁴
- −10⁷ ≤ aᵢ ≤ 10⁷
- An empty side sums to 0 (so for n = 1 the answer is always YES).
Samples
Input 1
6 1 7 3 6 5 6
Output 1
YES
Input 2
3 1 2 3
Output 2
NO
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