Find the leftmost digit that occurs in a given string.

Example

• For inputString = "var_1__Int", the output should be**solution(inputString) = '1'**;
• For inputString = "q2q-q", the output should be**solution(inputString) = '2'**;
• For inputString = "0ss", the output should be**solution(inputString) = '0'**.

Input/Output

• [execution time limit] 3 seconds (java)

• [memory limit] 1 GB

• [input] string inputString

  A string containing at least one digit.

  Guaranteed constraints:

  3 ≤ inputString.length ≤ 10.

• [output] char

풀이

char solution(String inputString) {
    String REGEXP_PATTERN_NUMBER = "^[\\\\d]*$";
    
    for(char c : inputString.toCharArray()) {
        boolean valid = Pattern.matches(REGEXP_PATTERN_NUMBER, Character.toString(c));
        
        if (valid) return c;
    }
    
    return 'a';
}