Binary Search and other algorithms implementations

ChapterTwoExercises.java

public class ChapterTwoExercises {

    /*
     * Binary search implementation, to know the steps necessary only double the
     * elements and plus 1
     * Array 3 = 2 steps
     * Array 7 = 3 steps
     * array 15 = 4 steps
     * array 31 = 5 steps
     * array 63 = 6 steps
     * array 127 = 7 steps
     * array 254 = 8 steps
     */
    public int binarySearch(int[] array, int target) {
        int lowerBound = 0;
        int upperBound = array.length - 1;

        while (lowerBound <= upperBound) {
            int midPoint = (upperBound + lowerBound) / 2;
            int valueAtMidpointPoint = array[midPoint];

            if (target == valueAtMidpointPoint) {
                return midPoint;
            }

            if (target < valueAtMidpointPoint) {
                upperBound = midPoint - 1;
            } else {
                lowerBound = midPoint + 1;
            }
        }

        return -1;
    }

    public int binarySearchTwo(int[] array, int target) {
        int left = 0;
        int right = array.length - 1;

        while (left <= right) {
            int mid = left + (right - left) / 2;

            if (array[mid] == target) {
                return mid;
            }

            if (array[mid] < target) {
                left = mid + 1;
            } else {
                right = mid - 1;
            }
        }

        return -1;
    }

    /*
     * Time complexity: O(N)
     */
    public int doubleSearch(int[] elements, int target) {
        int leftPointer = 0;
        int rightPointer = elements.length - 1;

        while (leftPointer <= rightPointer) {
            if (elements[leftPointer] == target) {
                return leftPointer;
            }

            if (elements[rightPointer] == target) {
                return rightPointer;
            }

            leftPointer++;
            rightPointer--;
        }

        return -1;
    }

    /*
     * Time complexity: O(N)
     */
    public String reverseString(String value) {
        StringBuilder builder = new StringBuilder();

        for (int i = value.length() - 1; i >= 0; i--) {
            char word = value.charAt(i);
            builder.append(word);
        }

        return builder.toString();
    }
}