Hacker be mitigated. White hats are usually employed by the target system's owner and are typically paid (sometimes quite well) for their work. Their work is not illegal because it is done with the system owner's consent. Black hats or crackers are hackers with malicious intentions. They often steal, exploit, and sell data, and are usually motivated by personal gain. Their work is usually illegal. A cracker is like a black hat hacker, but is specifically someone who is very skilled and tries via hacking to make profits or to benefit, not just to vandalize. Crackers find exploits for system vulnerabilities
Prefix sum are calculated in the first pass on each processing unit; the prefix sum of these partial sums is then calculated and broadcast back to the processing units for a second pass using the now known prefix as the initial value. Asymptotically this method takes approximately two read operations and one write operation per item. When a data set may be updated dynamically, it may be stored in a Fenwick tree data structure. This structure allows both the lookup of any individual prefix sum value and the modification of any array value in logarithmic time per operation.. However, an earlier 1982