CF1270G Subset with Zero Sum

You are given $ n $ integers $ a_1, a_2, \dots, a_n $ , such that for each $ 1\le i \le n $ holds $ i-n\le a_i\le i-1 $ . Find some nonempty subset of these integers, whose sum is equal to $ 0 $ . It can be shown that such a subset exists under given constraints. If there are several possible subsets with zero-sum, you can find any of them.

N/A

N/A

In the first example, we get sum is $ a_1 = 0 $ . In the second example, we get sum is $ a_1 + a_4 + a_3 + a_2 = 0 $ .