Fibonacci: three things that go wrong
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1) HashMap.computeIfAbsent as the memo, recursive mapping function, n = 10
   -> java.util.ConcurrentModificationException
   same idea written as get / compute / put -> 55

2) The answer outgrows a long
   fib(92) = 7540113804746346429
   fib(93) -> ArithmeticException: long overflow   (Math.addExact refuses to wrap around)
   plain + instead of addExact would silently return -6246583658587674878

3) Recursion depth, House Robber with every house worth 1, in a thread with a 256 KB stack
   memo       n =    500 -> 250
   memo       n = 50,000 -> java.lang.StackOverflowError
   tabulation n = 50,000 -> 25000