Strobogrammatic Number

A strobogrammatic number is a number that looks the same when rotated 180 degrees (looked at upside down).

Write a function to determine if a number is strobogrammatic. The number is represented as a string.

For example, the numbers "69", "88", and "818" are all strobogrammatic.

Tips:

走一遍，只要左右不是00 11 88 696就是错的。

Code：

public class Solution {
    public boolean isStrobogrammatic(String num) {
        if (num == null || num.length() == 0) {
            return true;
        }
        int left = 0, right = num.length() - 1;
        while (left <= right) {
            if (!"00 11 88 696".contains(num.charAt(left) + "" + num.charAt(right))) {
                return false;
            }
            left++;
            right--;
        }
        return true;
    }
}