246 Strobogrammatic Number I

246  Strobogrammatic Number I

/ / ac 
class Solution {
    public boolean isStrobogrammatic(String num) {
      HashMap<Character, Character> map = new HashMap<>();
      map.put('0','0');
      map.put('1','1');
      map.put('6','9');
      map.put('9','6');
      map.put('8','8');
      int i = 0;
      int j = num.length() - 1;
      while(i <= j){
        if(!map.containsKey(num.charAt(i))) return false;
        //  if(num.charAt(i) != map.get(num.charAt(j))){. This ape
        if(map.get(num.charAt(i)) != num.charAt(j)){
          return false;
        }
        i++;
        j--;
      }
      return true;
    }
}

 

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"
Output: true

Example 2:

Input:  "88"
Output: true

Example 3:

Input:  "962"
Output: false