Binary Search

// Zerethon Official Sample: binary-search 1.0.0 (view only — the IDE cannot run Java yet).
public class BinarySearch {
    // a must be sorted ascending. Returns the index of target, or -1.
    static int binarySearch(int[] a, int target) {
        int lo = 0, hi = a.length - 1;
        while (lo <= hi) {
            int mid = (lo + hi) >>> 1;
            if (a[mid] == target) return mid;
            if (a[mid] < target) lo = mid + 1;
            else hi = mid - 1;
        }
        return -1;
    }

    public static void main(String[] args) {
        int[] numbers = {2, 5, 8, 12, 16, 23, 38, 56, 72, 91};
        for (int target : new int[] {23, 2, 91, 7}) {
            int index = binarySearch(numbers, target);
            System.out.println("search " + target + ": " + (index == -1 ? "not found" : "found at index " + index));
        }
    }
}