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.

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