Problem

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.

Example 1:

Input: "69"

Input: "88"

Input: "962"

Solution

class Solution {    public boolean isStrobogrammatic(String s) {        //69, 88, 00, 11, 6969, 698869, 69869, 6908069, 886988        Map
    
      map = new HashMap<>();        map.put('6', '9');        map.put('9', '6');        map.put('0', '0');        map.put('1', '1');        map.put('8', '8');        int i = 0, j = s.length()-1;        while (i <= j) {            if (!map.containsKey(s.charAt(i))) return false;            if (map.get(s.charAt(i++)) != s.charAt(j--)) return false;        }        return true;    }}