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package com.search;

/**

* Binary search is an algorithm which finds the position of a target value within a sorted array

* <p>

* Worst-case performance O(log n)

* Best-case performance O(1)

* Average performance O(log n)

* Worst-case space complexity O(1)

*/

public final class BinarySearch {

/**

* @param array is an array where the element should be found

* @param key is an element which should be found

* @param <T> is any comparable type

* @return index of the element

*/

public static <T extends Comparable<T>> int findIndex(T[] array, T key) {

return search(array, key, 0, array.length - 1);

}

/**

* @param array The array to search

* @param key The element you are looking for

* @param left The lower bound

* @param right The upper bound

* @return the location of the key

**/

private static <T extends Comparable<T>> int search(T[] array, T key, int left, int right) {

if (left > right) {

return -1; // Key not found

}

// Find median

int median = left + (right - left) / 2;

int comp = key.compareTo(array[median]);

if (comp < 0) {

return search(array, key, left, median - 1);

}

if (comp > 0) {

return search(array, key, median + 1, right);

}

return median;

}

}