二分算法

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        int[] arr = {6, 12, 33, 87, 90, 97, 108, 561};
        int i = binarySearch(arr, 87);
        for (int j = 0; j <arr.length ; j++) {
            Log.d("hh",arr[j]+"");
        }


    }

    public static int binarySearch(int[] arr, int x) {
        int low = 0;
        int high = arr.length - 1;
        while (low <= high) {
            int middle = (low + high) / 2;
            if (x == arr[middle]) {
                return middle;
            } else if (x < arr[middle]) {
                high = middle - 1;
            } else {
                low = middle + 1;
            }
        }
        return -1;
    }

}