TL;DR: The fastest algorithm looks at every element once, keeping track of the largest one seen so far. Details. Intuition tells us that any correct algorithm must look at every element in the array, that's why we can't do better. Let's find an actual proof.
Drugs are addictive  because they either mimic or stimulate the production of brain chemicals that cause feelings of pleasure. After a period of time, your brain adjusts to the higher levels of the chemicals, and it becomes necessary to use more drugs to get the same effect.
3. Yes. Long-term use of marijuana leads to addiction in some people. Some people donât believe that you cannot be physically addicted to marijuana the way that people are addicted to other drugs. But this is not true.