Changed example.R implementation to pass new tests

exercises/practice/phone-number/.meta/example.R

@@ -1,35 +1,7 @@
 parse_phone_number <- function(number_string) {
-
-  # If the number is less than 10 digits assume that it is bad number
-  # If the number is 10 digits assume that it is good, unless area or exchange 
-  #  code are not between 2 to 9
-  # If the number is 11 digits and the first number is 1, use the last 10 digits
-  # If the number is 11 digits and the first number is not 1, it is a bad number
-  # If the number is more than 11 digits assume that it is a bad number
-
-  # Check for letters
-  if (grepl("[A-z]", number_string)) {
-    return (NULL)
-  }
-
-  # Remove non-digit characters from number string
-  cleaned <- gsub("[^0-9]", "", number_string)
-
-  if (nchar(cleaned) < 10) {
-    NULL
-  }
-  else if (nchar(cleaned) == 10 & (substr(cleaned, 1, 1) %in% c("0", "1") |
-                                   substr(cleaned, 4, 4) %in% c("0", "1"))) {
-    NULL
-  } 
-  else if (nchar(cleaned) == 10) {
-    cleaned
-  } 
-  else if (nchar(cleaned) == 11 & substr(cleaned, 1, 1) == "1") {
-    substr(cleaned, 2, 11)
-  }
-  else {
-    NULL
-  }
-
+  str <- gsub("\\D", replacement = "", number_string)
+  if (substr(str, 1, 1) == '1') str <- substr(str, 2, nchar(str))
+  if (nchar(str) != 10) return(NULL)
+  if (strtoi(substr(str, 1, 1)) < 2 || strtoi(substr(str, 4, 4)) < 2) return(NULL)
+  str
 }