A-M baby

Task/Fibonacci-sequence/Java/fibonacci-sequence-1.java

@@ -0,0 +1,15 @@
+public static long itFibN(int n)
+{
+ if (n < 2)
+  return n;
+ long ans = 0;
+ long n1 = 0;
+ long n2 = 1;
+ for(n--; n > 0; n--)
+ {
+  ans = n1 + n2;
+  n1 = n2;
+  n2 = ans;
+ }
+ return ans;
+}

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

@@ -0,0 +1,4 @@
+public static long recFibN(final int n)
+{
+ return (n < 2) ? n : recFibN(n - 1) + recFibN(n - 2);
+}

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

@@ -0,0 +1,6 @@
+public static long anFibN(final long 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));
+}

Task/Fibonacci-sequence/Java/fibonacci-sequence-4.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);
+}