solves alien language dictionary

Author: anishLearnsToCode

README.md

@@ -258,7 +258,7 @@
 | 942 | [DI String Match](https://leetcode.com/problems/di-string-match) | [![Java](assets/java.png)](src/DIStringMatch.java) |
 | 944 | [Delete Columns to Make Sorted](https://leetcode.com/problems/delete-columns-to-make-sorted) | [![Java](assets/java.png)](src/DeleteColumnsToMakeSorted.java) |
 | 949 | [Largest Time for Given Digits](https://leetcode.com/problems/largest-time-for-given-digits) | |
-| 953 | [Verifying an Alien Dictionary](https://leetcode.com/problems/verifying-an-alien-dictionary) | |
+| 953 | [Verifying an Alien Dictionary](https://leetcode.com/problems/verifying-an-alien-dictionary) | [![Java](assets/java.png)](src/VerifyAnAlienDictionary.java) |
 | 961 | [N-Repeated Elements in Size 2N Array](https://leetcode.com/problems/n-repeated-element-in-size-2n-array) | |
 | 965 | [Univalued Binary Tree](https://leetcode.com/problems/univalued-binary-tree) | |
 | 970 | [Powerful Integers](https://leetcode.com/problems/powerful-integers) | |

src/VerifyAnAlienDictionary.java

@@ -0,0 +1,33 @@
+import java.util.Comparator;
+
+public class VerifyAnAlienDictionary {
+    public boolean isAlienSorted(String[] words, String order) {
+        AlienLanguageComparator alienLanguageComparator = new AlienLanguageComparator(order);
+        for (int i = 1 ; i < words.length ; i++) {
+            if (alienLanguageComparator.compare(words[i - 1], words[i]) > 0) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    private static class AlienLanguageComparator implements Comparator<String> {
+        final int[] characterOrder = new int[26];
+
+        AlienLanguageComparator(String order) {
+            for (int index = 0 ; index < 26 ; index++) {
+                characterOrder[order.charAt(index) - 'a'] = index;
+            }
+        }
+
+        @Override
+        public int compare(String s1, String s2) {
+            if (s1.length() == s2.length() && s1.equals(s2)) return 0;
+            for (int i = 0, j = 0 ; i < s1.length() && j < s2.length() ; i++, j++) {
+                if (characterOrder[s1.charAt(i) - 'a'] < characterOrder[s2.charAt(j) - 'a']) return -1;
+                else if (characterOrder[s1.charAt(i) - 'a'] > characterOrder[s2.charAt(j) - 'a']) return 1;
+            }
+            return s1.length() - s2.length();
+        }
+    }
+}