Add solution #831

Author: JoshCrozier

README.md

@@ -29,6 +29,7 @@
 804|[Unique Morse Code Words](./0804-unique-morse-code-words.js)|Easy|
 819|[Most Common Word](./0819-most-common-word.js)|Easy|
 824|[Goat Latin](./0824-goat-latin.js)|Easy|
+831|[Masking Personal Information](./0831-masking-personal-information.js)|Medium|
 890|[Find and Replace Pattern](./0890-find-and-replace-pattern.js)|Medium|
 916|[Word Subsets](./0916-word-subsets.js)|Medium|
 929|[Unique Email Addresses](./0929-unique-email-addresses.js)|Easy|

solutions/0831-masking-personal-information.js

@@ -0,0 +1,57 @@
+/**
+ * 831. Masking Personal Information
+ * https://leetcode.com/problems/masking-personal-information/
+ * Difficulty: Medium
+ *
+ * We are given a personal information string S, which may represent either an email address or a phone number.
+ * We would like to mask this personal information according to the following rules:
+ * 1. Email address:
+ * We define a name to be a string of length ≥ 2 consisting of only lowercase letters a-z or uppercase letters A-Z.
+ * An email address starts with a name, followed by the symbol '@', followed by a name, followed by the dot '.' and
+ * followed by a name. All email addresses are guaranteed to be valid and in the format of "[email protected]".
+ * To mask an email, all names must be converted to lowercase and all letters between the first and last letter of
+ * the first name must be replaced by 5 asterisks '*'.
+ *
+ * 2. Phone number:
+ * A phone number is a string consisting of only the digits 0-9 or the characters from the set
+ * {'+', '-', '(', ')', ' '}. You may assume a phone number contains 10 to 13 digits. The last 10 digits make up the
+ * local number, while the digits before those make up the country code. Note that the country code is optional. We
+ * want to expose only the last 4 digits and mask all other digits. The local number should be formatted and masked
+ * as "***-***-1111", where 1 represents the exposed digits. To mask a phone number with country code like
+ * "+111 111 111 1111", we write it in the form "+***-***-***-1111".  The '+' sign and the first '-' sign before the
+ * local number should only exist if there is a country code.  For example, a 12 digit phone number mask should start
+ * with "+**-". Note that extraneous characters like "(", ")", " ", as well as extra dashes or plus signs not part of
+ * the above formatting scheme should be removed.
+ *
+ * Return the correct "mask" of the information provided.
+ */
+
+// The one-line solution:
+/**
+ * @param {string} S
+ * @return {string}
+ */
+var maskPII = function(S) {
+  return S.toLowerCase()
+    .replace(/^([a-z])[a-z]*([a-z])/, '$1*****$2')
+    .replace(/[)(\-\s+]+/g, '')
+    .replace(/^(\d*)(\d{3})(\d{3})(\d{4})$/, '+$1-$2-$3-$4')
+    .replace(/\d(?!\d{0,3}$)/g, '*')
+    .replace(/^\+\-/, '');
+};
+
+// More readable alternative:
+/**
+ * @param {string} S
+ * @return {string}
+ */
+var maskPII = function(S) {
+  if (S.includes('@')) {
+    return S.toLowerCase().replace(/^(\w)\w*(\w)/, '$1*****$2');
+  } else {
+    return S.replace(/\D+/g, '')
+      .replace(/^(\d*)(\d{3})(\d{3})(\d{4})$/, '+$1-$2-$3-$4')
+      .replace(/\d(?!\d{0,3}$)/g, '*')
+      .replace(/^\+\-/, '');
+  }
+};