Added Java Recursion Example of Greatest Common Divisor, Issue#64

Java/Recursion/GCD.java

@@ -0,0 +1,16 @@
+public class GCD {
+
+    // Recursive function to find GCD
+    static int gcd(int a, int b) {
+        if (b == 0)
+            return a;
+        return gcd(b, a % b);
+    }
+
+    public static void main(String[] args) {
+        int num1 = 48;
+        int num2 = 18;
+
+        System.out.println("GCD of " + num1 + " and " + num2 + " is: " + gcd(num1, num2));
+    }
+}

Java/Recursion/countAndSay.java

@@ -0,0 +1,41 @@
+package Recusrion;
+
+public class countAndSay {
+    public String __countAndSay__(int n) {
+        return countAndMerge(n);
+    }
+
+    private static String countAndMerge(int n) {
+        if (n == 1)
+            return "1";
+        else if (n == 2)
+            return "11";
+        else if (n == 3)
+            return "21";
+        else if (n == 4)
+            return "1211";
+        else {
+            StringBuilder answer = new StringBuilder();
+            String xyz = (countAndMerge(n - 1));
+            int[] helper = new int[10];
+            int prev = xyz.charAt(0) - '0';
+            for (int i = 0; i < xyz.length(); i++) {
+                int current = xyz.charAt(i) - '0';
+                helper[xyz.charAt(i) - '0']++;
+                if (prev != current) {
+                    answer.append(helper[prev]);
+                    answer.append(prev);
+                    helper[prev] = 0;
+                    prev = current;
+                }
+                if (i == xyz.length() - 1) {
+                    answer.append(helper[xyz.charAt(i) - '0']);
+                    answer.append(xyz.charAt(i));
+                }
+            }
+
+            return answer.toString();
+
+        }
+    }
+}