Is the following problem NP-hard:Input: $A\subset\mathbb Z, k\in\mathbb N$Question: is there a multiset of indices $I$, such that $|I|=k$ and $\sum_{i\in I} a_i=0$?For example, on the input $A=\{-1,2\}, k=3$ we can take $I=\{1,1,2\}$ and thus we get $|I|=3$ and $a_1+a_1+a_2=(-1)+(-1)+2=0$, as desired.
Is the following Subset Sum variant NP-complete?
complexity theory;time complexity;np complete;np hard;decision problem