Added String Problem-Solution

Co-authored-by: Ashish Kumar Singh <ashishk.singh1008@gmail.com>
Co-authored-by: Laxman Singh Koranga <laxmankoranga03@gmail.com>

Author: lxmn22nov

Java/String/ReverseString.java

@@ -0,0 +1,14 @@
+/*
+ * PROBLEM: 344: Reverse String
+ */
+public class ReverseString {
+    public void reverseString(char[] s) {
+        int start = 0;
+        int end = s.length - 1;
+        while (start < end) {
+            char temp = s[start];
+            s[start++] = s[end];
+            s[end--] = temp;
+        }
+    }
+}