72 lines
2.2 KiB
Java
72 lines
2.2 KiB
Java
package Searches;
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/*
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* Fibonacci Search is a popular algorithm which finds the position of a target value in
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* a sorted array
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*
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* The time complexity for this search algorithm is O(log3(n))
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* The space complexity for this search algorithm is O(1)
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* @author Kanakalatha Vemuru (https://github.com/KanakalathaVemuru)
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*/
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public class FibonacciSearch implements SearchAlgorithm {
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/**
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* @param array is a sorted array where the element has to be searched
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* @param key is an element whose position has to be found
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* @param <T> is any comparable type
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* @return index of the element
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*/
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@Override
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public <T extends Comparable<T>> int find(T[] array, T key) {
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int fibMinus1 = 1;
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int fibMinus2 = 0;
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int fibNumber = fibMinus1 + fibMinus2;
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int n = array.length;
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while (fibNumber < n) {
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fibMinus2 = fibMinus1;
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fibMinus1 = fibNumber;
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fibNumber = fibMinus2 + fibMinus1;
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}
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int offset = -1;
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while (fibNumber > 1) {
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int i = Math.min(offset + fibMinus2, n - 1);
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if (array[i].compareTo(key) < 0) {
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fibNumber = fibMinus1;
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fibMinus1 = fibMinus2;
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fibMinus2 = fibNumber - fibMinus1;
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offset = i;
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}
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else if (array[i].compareTo(key) > 0) {
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fibNumber = fibMinus2;
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fibMinus1 = fibMinus1 - fibMinus2;
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fibMinus2 = fibNumber - fibMinus1;
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}
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else {
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return i;
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}
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}
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if (fibMinus1 == 1 && array[offset + 1] == key) {
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return offset + 1;
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}
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return -1;
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}
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// Driver Program
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public static void main(String[] args) {
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Integer[] integers = {1, 2, 4, 8, 16, 32, 64, 128, 256, 512};
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int size = integers.length;
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Integer shouldBeFound = 128;
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FibonacciSearch fsearch = new FibonacciSearch();
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int atIndex = fsearch.find(integers, shouldBeFound);
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System.out.println(
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"Should be found: " + shouldBeFound + ". Found "+ integers[atIndex] + " at index "+ atIndex +". An array length " + size);
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}
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} |