二分查找

private static int myBinarySearch(int [] array , int k) {
        int low = 0;
        int high = array.length - 1;
        while(low <= high) {
            int mid = (low + high) / 2;
            if(array[mid] == k) {
                return mid;
            } else if(array[mid] < k) {
                low = mid + 1;
            } else {
                high = mid - 1;
            }
        }
        return -1;
    }