二分查找

    public static boolean BinarySearch(int[] array, int target) {
        boolean find = false;
        if (array == null || array.length < 1) {
            return false;
        }
        int start = 0;
        int end = array.length - 1;
        while (start <= end) {  // 这里必须是 <=  ,很重要
            int mid = start + (end - start) / 2;
            if (target < array[mid]) {
                end = mid - 1;
            } else if (target > array[mid]) {
                start = mid + 1;
            } else {
                find = true;
                break;
            }
        }
        return find;
    }