easy stringbuilder solution (java)
IntuitionApproachComplexity
Time complexity:

Space complexity:
Code
# Intuition
<!-- Describe your first thoughts on how to solve this problem. -->

# Approach
<!-- Describe your approach to solving the problem. -->

# Complexity
- Time complexity:
<!-- Add your time complexity here, e.g. $$O(n)$$ -->

- Space complexity:
<!-- Add your space complexity here, e.g. $$O(n)$$ -->

# Code
```java []
class Solution {
    public boolean hasSameDigits(String s) {
        int n = s.length();
        while (n > 2) {
            StringBuilder sb = new StringBuilder();

            for (int i = 0; i < n - 1; i++) {
                int sum = (int)(s.charAt(i) - '0') + (int)(s.charAt(i + 1) - '0');
                sb.append(sum % 10);
            }

            s = sb.toString();
            n = sb.length();
        }

        return s.charAt(0) == s.charAt(1);
    }
}
```
['Java']