diff --git a/Searches/ExponentalSearch.java b/Searches/ExponentalSearch.java new file mode 100644 index 000000000..4b8e7afca --- /dev/null +++ b/Searches/ExponentalSearch.java @@ -0,0 +1,59 @@ +package Searches; + +import java.util.Arrays; +import java.util.Random; +import java.util.concurrent.ThreadLocalRandom; +import java.util.stream.IntStream; + +import static java.lang.String.format; + +class ExponentialSearch implements SearchAlgorithm { + + public static void main(String [] args) { + Random r = ThreadLocalRandom.current(); + + int size = 100; + int maxElement = 100000; + + Integer[] integers = + IntStream.generate(() -> r.nextInt(maxElement)) + .limit(size) + .sorted() + .boxed() + .toArray(Integer[]::new); + + // The element that should be found + int shouldBeFound = integers[r.nextInt(size - 1)]; + + ExponentialSearch search = new ExponentialSearch(); + int atIndex = search.find(integers, shouldBeFound); + + System.out.println( + format( + "Should be found: %d. Found %d at index %d. An array length %d", + shouldBeFound, integers[atIndex], atIndex, size)); + + int toCheck = Arrays.binarySearch(integers, shouldBeFound); + System.out.println( + format( + "Found by system method at an index: %d. Is equal: %b", toCheck, toCheck == atIndex)); + + } + + @Override + public > int find(T[] array, T key) { + if (array[0] == key) + return 0; + if (array[array.length - 1] == key) + return array.length; + + int range = 1; + + + while (range < array.length && array[range].compareTo(key) <= -1) { + range = range * 2; + } + + return Arrays.binarySearch(array, range / 2, Math.min(range, array.length), key); + } +}