Data commit

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 +1,28 @@
+/**
+ * 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

@@ -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-4.java

@@ -0,0 +1,18 @@
+public class Fibonacci {
+
+    static final Map<Integer, Long> cache = new HashMap<>();
+    static {
+        cache.put(1, 1L);
+        cache.put(2, 1L);
+    }
+
+    public static long get(int n)
+    {
+        return (n < 2) ? n : impl(n);
+    }
+
+    private static long impl(int n)
+    {
+        return cache.computeIfAbsent(n, k -> impl(k-1) + impl(k-2));
+    }
+}

Task/Fibonacci-sequence/Java/fibonacci-sequence-5.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-6.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);
+}

Task/Fibonacci-sequence/Java/fibonacci-sequence-7.java

@@ -0,0 +1,18 @@
+import java.util.function.LongUnaryOperator;
+import java.util.stream.LongStream;
+
+public class FibUtil {
+ public static LongStream fibStream() {
+  return LongStream.iterate( 1l, new LongUnaryOperator() {
+   private long lastFib = 0;
+   @Override public long applyAsLong( long operand ) {
+    long ret = operand + lastFib;
+    lastFib = operand;
+    return ret;
+   }
+  });
+ }
+ public static long fib(long n) {
+  return fibStream().limit( n ).reduce((prev, last) -> last).getAsLong();
+ }
+}