Merge pull request #724 from hizkiajuan/hizkiajuan_fibonacci_variant_in_java

Uploaded fibonacci variant program in Java

Author: t2013anurag

fibonacci/java/fibonacci_dp.java

@@ -0,0 +1,23 @@
+// Objective : get nth Fibonacci number
+// Method    : dynamic programming
+
+class fibonacci_dp {
+   static int fib(int n) {
+        int f[] = new int[n+1];
+        int i;
+      
+        f[0] = 0;
+        f[1] = 1;
+     
+        for (i = 2; i <= n; i++) {
+            f[i] = f[i-1] + f[i-2];
+        }
+        
+        return f[n];
+    }
+      
+    public static void main (String args[]) {
+        int n = 9;
+        System.out.println(fib(n));
+    }
+}

fibonacci/java/fibonacci_dp_space_optimized.java

@@ -0,0 +1,22 @@
+// Objective : get nth Fibonacci number
+// Method    : dynamic programming (space optimized)
+
+class fibonacci_dp_space_optimized {
+    static int fib(int n) {
+        int a = 0, b = 1, c;
+        
+        if (n == 0) return a;
+        for (int i = 2; i <= n; i++) {
+            c = a + b;
+            a = b;
+            b = c;
+        }
+
+        return b;
+    }
+ 
+    public static void main (String args[]) {
+        int n = 9;
+        System.out.println(fib(n));
+    }
+}

fibonacci/java/fibonacci_matrix.java

@@ -0,0 +1,41 @@
+// Objective : get nth Fibonacci number
+// Method    : matrix
+
+class fibonacci_matrix {
+    static int fib(int n) {
+        int F[][] = new int[][]{{1,1},{1,0}};
+        
+        if (n == 0) return 0;
+        power(F, n-1);
+     
+        return F[0][0];
+    }
+      
+    // helper
+    static void multiply(int F[][], int M[][]) {
+        int x =  F[0][0]*M[0][0] + F[0][1]*M[1][0];
+        int y =  F[0][0]*M[0][1] + F[0][1]*M[1][1];
+        int z =  F[1][0]*M[0][0] + F[1][1]*M[1][0];
+        int w =  F[1][0]*M[0][1] + F[1][1]*M[1][1];
+          
+        F[0][0] = x;
+        F[0][1] = y;
+        F[1][0] = z;
+        F[1][1] = w;
+    }
+ 
+    // helper
+    static void power(int F[][], int n) {
+        int i;
+        int M[][] = new int[][]{{1,1},{1,0}};
+     
+        for (i = 2; i <= n; i++) {
+            multiply(F, M);
+        }
+    }
+      
+    public static void main (String args[]) {
+        int n = 9;
+        System.out.println(fib(n));
+    }
+}

fibonacci/java/fibonacci_matrix_time_optimized.java

@@ -0,0 +1,42 @@
+// Objective : get nth Fibonacci number
+// Method    : matrix (time optimized)
+
+class fibonacci_matrix_time_optimized {
+    static int fib(int n) {
+        int F[][] = new int[][]{{1,1},{1,0}};
+
+        if (n == 0) return 0;
+        power(F, n-1);
+      
+        return F[0][0];
+    }
+      
+    // helper
+    static void multiply(int F[][], int M[][]) {
+        int x =  F[0][0]*M[0][0] + F[0][1]*M[1][0];
+        int y =  F[0][0]*M[0][1] + F[0][1]*M[1][1];
+        int z =  F[1][0]*M[0][0] + F[1][1]*M[1][0];
+        int w =  F[1][0]*M[0][1] + F[1][1]*M[1][1];
+         
+        F[0][0] = x;
+        F[0][1] = y;
+        F[1][0] = z;
+        F[1][1] = w;
+    }
+      
+    // helper -- optimized
+    static void power(int F[][], int n) {
+        if( n == 0 || n == 1) return;
+        int M[][] = new int[][]{{1,1},{1,0}};
+      
+        power(F, n/2);
+        multiply(F, F);
+      
+        if(n%2 != 0) multiply(F, M);
+    }
+     
+    public static void main (String args[]) {
+        int n = 9;
+        System.out.println(fib(n));
+    }
+}

fibonacci/java/fibonacci_recursion.java

@@ -0,0 +1,14 @@
+// Objective : get nth Fibonacci number
+// Method    : recursion
+
+class fibonacci_recursion {
+    static int fib(int n) {
+        if (n <= 1) return n;
+        return fib(n-1) + fib(n-2);
+    }
+      
+    public static void main (String args[]) {
+        int n = 9;
+        System.out.println(fib(n));
+    }
+}