Just another update

Task/Fibonacci-sequence/Java/fibonacci-sequence-2.java

@@ -1,4 +1,28 @@
-public static long recFibN(final int n)
-{
- return (n < 2) ? n : recFibN(n - 1) + recFibN(n - 2);
+/**
+ * O(log(n))
+ */
+public static long fib(long n) {
+    if (n <= 0)
+	return 0;
+
+    long i = (int) (n - 1);
+    long a = 1, b = 0, c = 0, d = 1, tmp1,tmp2;
+
+    while (i > 0) {
+	if (i % 2 != 0) {
+            tmp1 = d * b + c * a;
+	    tmp2 = d * (b + a) + c * b;
+	    a = tmp1;
+	    b = tmp2;
+	}
+
+        tmp1 = (long) (Math.pow(c, 2) + Math.pow(d, 2));
+        tmp2 = d * (2 * c + d);
+			
+        c = tmp1;
+        d = tmp2;
+
+        i = i / 2;
+    }
+    return a + b;
 }

Task/Fibonacci-sequence/Java/fibonacci-sequence-3.java

@@ -1,6 +1,4 @@
-public static long anFibN(final long n)
+public static long recFibN(final int n)
 {
- double p = (1 + Math.sqrt(5)) / 2;
- double q = 1 / p;
- return (long) ((Math.pow(p, n) + Math.pow(q, n)) / Math.sqrt(5));
+ return (n < 2) ? n : recFibN(n - 1) + recFibN(n - 2);
 }

Task/Fibonacci-sequence/Java/fibonacci-sequence-4.java

@@ -1,9 +1,6 @@
-public static long fibTailRec(final int n)
+public static long anFibN(final long n)
 {
- return fibInner(0, 1, n);
-}
-
-private static long fibInner(final long a, final long b, final int n)
-{
- return n < 1 ? a : n == 1 ?  b : fibInner(b, a + b, n - 1);
+ double p = (1 + Math.sqrt(5)) / 2;
+ double q = 1 / p;
+ return (long) ((Math.pow(p, n) + Math.pow(q, n)) / Math.sqrt(5));
 }

Task/Fibonacci-sequence/Java/fibonacci-sequence-5.java

@@ -0,0 +1,9 @@
+public static long fibTailRec(final int n)
+{
+ return fibInner(0, 1, n);
+}
+
+private static long fibInner(final long a, final long b, final int n)
+{
+ return n < 1 ? a : n == 1 ?  b : fibInner(b, a + b, n - 1);
+}