CountDigits/Algorithm.java

public class Algorithm {
    // Nr 2
    public int binarySearch(int[] arr, int left, int right, int target) {
        if (left > right) {
            return -1;
        }

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

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

        if (target < arr[mid]) {
            return binarySearch(arr, left, mid - 1, target);
        }

        return binarySearch(arr, mid + 1, right, target);
    }

    // NR 1
    public int ggt(int m, int n) {
        while (n != 0) {
            int rest = m % n;
            m = n;
            n = rest;
        }
        return m;
    }

    // NR 3
    public long potenz(long a, int b) {
        if (b == 0) {
            return 1;
        }
        return a * potenz(a, b - 1);
    }
}