Efficient algorithm for determining if $\pm c_1 \pm c_2 \dots \pm c_n = 0$ Suppose that we're given $n$ integers $c_1, c_2, \dots, c_n$. We want
  to know if there is any assignment of $+$ and $-$ signs such that
  
  $$ \pm c_1 \pm c_2 \dots \pm c_n = 0. $$


Does anyone know of a polynomial-time way to do this? Since there are $n$ integers, there are $2^n$ assignments of signs to consider, which grows rather quickly.

I've tried to phrase this problem in such a way that I can make use of dynamic programming, but DP usually lends itself to optimization sorts of problems, and this problem does not fall into that category (at least as stated).
Hint: This is just the well-known NP-complete problem PARTITION.