solves ##408: Valid word abbreviation in java

Author: anishLearnsToCode

README.md

@@ -313,7 +313,7 @@
 | 401  | [Binary Watch](https://leetcode.com/problems/binary-watch)                                                                                                             |                                                             [![Java](assets/java.png)](src/BinaryWatch.java) [![Python](assets/python.png)](python/binary_watch.py)                                                              |                                                                                                                                   |
 | 404  | [Sum of Left Leaves](https://leetcode.com/problems/sum-of-left-leaves)                                                                                                 |                                                        [![Java](assets/java.png)](src/SumOfLeftLeaves.java) [![Python](assets/python.png)](python/sum_of_left_leaves.py)                                                         |                                                                                                                                   |
 | 405  | [Convert a Number to Hexadecimal](https://leetcode.com/problems/convert-a-number-to-hexadecimal)                                                                       |                                            [![Java](assets/java.png)](src/ConvertNumberToHexadecimal.java) [![Python](assets/python.png)](python/convert_a_number_to_hexadecimal.py)                                             |                                                                                                                                   |
-| 408  | 🔒 [Valid Word Abbreviation](https://leetcode.com/problems/valid-word-abbreviation)                                                                                    |                                                                                                                                                                                                                                  |                                                                                                                                   |
+| 408  | 🔒 [Valid Word Abbreviation](https://leetcode.com/problems/valid-word-abbreviation)                                                                                    |                                                                                    [![Java](assets/java.png)](src/ValidWordAbbreviation.java)                                                                                    |                                                                                                                                   |
 | 409  | [Longest Palindrome](https://leetcode.com/problems/longest-palindrome)                                                                                                 |                                                       [![Java](assets/java.png)](src/LongestPalindrome.java) [![Python](assets/python.png)](python/longest_palindrome.py)                                                        |                                                                                                                                   |
 | 412  | [Fizz Buzz](https://leetcode.com/problems/fizz-buzz)                                                                                                                   |                                                                [![Java](assets/java.png)](src/FizzBuzz.java) [![Python](assets/python.png)](python/fizz_buzz.py)                                                                 |                                                                                                                                   |
 | 414  | [Third Maximum Number](https://leetcode.com/problems/third-maximum-number)                                                                                             |                                                           [![Java](assets/java.png)](src/ThirdMaximumNumber.java) [![Python](assets/python.png)](python/fizz_buzz.py)                                                            |                                                                                                                                   |

src/ValidWordAbbreviation.java

@@ -0,0 +1,35 @@
+// https://leetcode.com/problems/valid-word-abbreviation
+// T: O(|word|)
+// S: O(1)
+
+public class ValidWordAbbreviation {
+    public boolean validWordAbbreviation(String word, String abbr) {
+        if(abbr.length() > word.length()) {
+            return false;
+        }
+
+        int i = 0, j = 0;
+        while(i < word.length() && j < abbr.length()) {
+            final char wc = word.charAt(i), ac = abbr.charAt(j);
+            // if both characters are different, return false
+            if(Character.isLetter(ac) && wc != ac) return false;
+            else{
+                // encountering a digit
+                if(Character.isDigit(ac)){
+                    int a = ac - '0';
+                    if(a == 0) return false;
+                    // while we get digits, we create bigger number
+                    while(j + 1 < abbr.length() && Character.isDigit(abbr.charAt(j + 1))){
+                        a = a * 10 + abbr.charAt(j + 1) - '0';
+                        j++;
+                    }
+                    // jump i end of digits position
+                    i += a - 1;
+                }
+            }
+            j++;
+            i++;
+        }
+        return i == word.length() && j == abbr.length();
+    }
+}