feat: add Determine if String Halves Are Alike LeetCode (#1168)

* add leetcode Determine if String Halves Are Alike

* fix variable  name

Co-authored-by: David Leal <halfpacho@gmail.com>

leetcode/DIRECTORY.md

@@ -106,6 +106,7 @@
 | 1769 | [Minimum Number of Operations to Move All Balls to Each Box](https://leetcode.com/problems/minimum-number-of-operations-to-move-all-balls-to-each-box/)                                     | [C](./src/1769.c) | Medium     |
 | 1524 | [Number of Sub-arrays With Odd Sum](https://leetcode.com/problems/number-of-sub-arrays-with-odd-sum/)                           | [C](./src/1524.c) | Medium     |
 | 1653 | [Minimum Deletions to Make String Balanced](https://leetcode.com/problems/minimum-deletions-to-make-string-balanced/)           | [C](./src/1653.c) | Medium     |
+| 1704 | [Determine if String Halves Are Alike](Determine if String Halves Are Alike)                                                    | [C](./src/1704.c) | Easy       |
 | 1752 | [Check if Array Is Sorted and Rotated](https://leetcode.com/problems/check-if-array-is-sorted-and-rotated/)                     | [C](./src/1752.c) | Easy       |
 | 2024 | [Maximize the Confusion of an Exam](https://leetcode.com/problems/maximize-the-confusion-of-an-exam/)                           | [C](./src/2024.c) | Medium     |
 | 2130 | [Maximum Twin Sum of a Linked List](https://leetcode.com/problems/maximum-twin-sum-of-a-linked-list/)                           | [C](./src/2130.c) | Medium     |

leetcode/src/1704.c

@@ -0,0 +1,38 @@
+bool isVowel(char chr){
+    switch(chr){
+        case 'a':
+        case 'e':
+        case 'i':
+        case 'o':
+        case 'u':
+        case 'A':
+        case 'E':
+        case 'I':
+        case 'O':
+        case 'U':
+            return true;
+    }
+    
+    return false;
+}
+
+// Counting
+// Runtime: O(n)
+// Space: O(1)
+bool halvesAreAlike(char * s){
+    int lenS = strlen(s);
+    int halfVowels = 0;
+    int currVowels = 0;
+    
+    for (int i = 0; i < lenS; i++){
+        if (isVowel(s[i])){
+            currVowels++;
+        }
+        
+        if (2 * (i + 1) == lenS){
+            halfVowels = currVowels;
+        }
+    }
+    
+    return 2 * halfVowels == currVowels;
+}