Add recursively reverse vector algorithm

Author: Alex0Blackwell

Algorithms/reverseStrRecursive.cpp

@@ -0,0 +1,22 @@
+class Solution {
+    void swap(char & a, char & b) {
+        char _tmp = a;
+        a = b;
+        b = _tmp;
+    }
+
+
+    void help(vector<char> & s, int left, int right) {
+        if(left >= right)
+            return;
+
+        swap(s[left], s[right]);
+
+        help(s, ++left, --right);
+    }
+
+public:
+    void reverseString(vector<char>& s) {
+        help(s, 0, s.size()-1);
+    }
+};

README.md

@@ -110,6 +110,9 @@ This repository is for small C and C++ programs I do outside of my school work.
     - reverse only the characters in the string
     - Leetcode problem found [here](https://leetcode.com/problems/reverse-only-letters/)
   - reverseStr.cpp
+  - reverseStrRecursive.cpp
+    - recursively reverse vector
+    - Leetcode problem found [here](https://leetcode.com/explore/learn/card/recursion-i/250/principle-of-recursion/1440/)
   - romanToDecimal.cpp
     - given roman numerals, return a decimal number
   - sortArrayByParity.cpp