Added hard/wildcard_characters

bradhanson · bradhanson · commit 5d8850c6a91b · 2018-07-08T09:32:39.000-04:00
diff --git a/hard/wildcard_characters.js b/hard/wildcard_characters.js
@@ -0,0 +1,69 @@
+/**
+ * Using the JavaScript language, have the function wildcardCharacters(str) read
+ * str which will contain two strings separated by a space. The first string
+ * will consist of the following sets of characters: +, *, and {N} which is
+ * optional. The plus (+) character represents a single alphabetic character,
+ * the asterisk (*) represents a sequence of the same character of length 3
+ * unless it is followed by {N} which represents how many characters should
+ * appear in the sequence where N will be at least 1. Your goal is to determine
+ * if the second string exactly matches the pattern of the first string in the
+ * input.
+ *
+ * For example: if str is "++*{5} gheeeee" then the second string in this case
+ * does match the pattern, so your program should return the string true. If the
+ * second string does not match the pattern your program should return the
+ * string false.
+ *
+ * https://coderbyte.com/results/bhanson:Wildcard%20Characters:JavaScript
+ *
+ * @param  {string} str
+ * @return {string} 'true' or 'false'
+ */
+function wildcardCharacters(str) {
+    // Separate inputs
+    const pair = str.split(' ');
+    const patternTokens = pair[0];
+    const matchString = pair[1];
+
+    // Step 1:  Build a regular expression from the given pattern
+    let matchRegex = '^';
+
+    for (let i = 0, n = 1; i < patternTokens.length; i++) {
+        switch (patternTokens[i]) {
+            case '+':
+                matchRegex += '[a-z]';
+                break;
+            case '*':
+                let repeat = 0;
+                if (tokenHasLengthParameter(i)) {
+                    // Custom length
+                    repeat = Number(str[i + 2]) - 1;
+                    i = i + 3;
+                } else {
+                    // Default length 3 (one letter plus two repeats)
+                    repeat = 2;
+                }
+
+                matchRegex += '([a-z])\\' + n++ + '{' + repeat + '}';
+                break;
+            default:
+                break;
+        }
+    }
+    matchRegex += '$';
+
+    // Step 2:  Apply regex to matchString and return results
+    matchRegex = new RegExp(matchRegex, 'i');
+    return String(matchRegex.test(matchString));
+
+    /* Helpers */
+
+    function tokenHasLengthParameter(index) {
+        if (index + 1 < patternTokens.length && str[index + 1] === '{') {
+            return true;
+        }
+        return false;
+    }
+}
+
+module.exports = wildcardCharacters;
diff --git a/hard/wildcard_characters.test.js b/hard/wildcard_characters.test.js
@@ -0,0 +1,24 @@
+const wildcardCharacters = require('./wildcard_characters');
+
+describe('wildcardCharacters()', () => {
+    test('correctly returns "true" for string matching pattern', () => {
+        expect(wildcardCharacters('**+*{2} mmmrrrkbb')).toBe('true');
+    });
+
+    test('correctly returns "false" for string not matching pattern', () => {
+        expect(wildcardCharacters('+++++* abcdemmmmmm')).toBe('false');
+    });
+
+    test('passes coderbyte.com tests', () => {
+        expect(wildcardCharacters('++*{5} gheeeee')).toBe('true');
+        expect(wildcardCharacters('+++++* abcdemmmmmm')).toBe('false');
+        expect(wildcardCharacters('**+*{2} mmmrrrkbb')).toBe('true');
+        expect(wildcardCharacters('+ a')).toBe('true');
+        expect(wildcardCharacters('*{1}*{1} rt')).toBe('true');
+        expect(wildcardCharacters('*+ vvr')).toBe('false');
+        expect(wildcardCharacters('* ttt')).toBe('true');
+        expect(wildcardCharacters('*{7} gggaggggg')).toBe('false');
+        expect(wildcardCharacters('+*{10}+ gphpppppppppp')).toBe('false');
+        expect(wildcardCharacters('****{4}+++ fffbbbeeerrrrmko')).toBe('true');
+    });
+});
