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Memoized Fibonacci calculation using lambdas in Java 8
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public class MemoizedLambdaFib { | |
interface MemoizedFunction<T, R> { | |
enum Cache { | |
_; | |
Map<Object, Object> vals = new HashMap<>(); | |
} | |
R calc(T t); | |
public default R apply(T t) { | |
if (!Cache._.vals.containsKey(t)) { | |
Cache._.vals.put(t, calc(t)); | |
} | |
return (R)Cache._.vals.get(t); | |
} | |
} | |
static final MemoizedFunction<Integer, Integer> fib = (Integer n) -> { | |
if (n == 0 || n == 1) return n; | |
return fib.apply(n - 1)+fib.apply(n-2); | |
}; | |
public static void main(String[] args) { | |
System.out.println(fib.apply(20)); | |
} | |
} |
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Great comment! Thank you for letting me know abou computeIfAbsent. Sorry I didn't see this sooner!