Added fibonacci sequence as well as fibonacci nth, renamed functions accordingly (trekhleb#36)

Author: ohepworthbell

src/algorithms/math/fibonacci/__test__/fibonacci.test.js

@@ -2,14 +2,13 @@ import fibonacci from '../fibonacci'
 
 describe('fibonacci',()=>{
 it('should calculate fibonacci correctly',()=>{
-expect(fibonacci(1)).toBe(1);
-expect(fibonacci(2)).toBe(1);
-expect(fibonacci(3)).toBe(2);
-expect(fibonacci(4)).toBe(3);
-expect(fibonacci(5)).toBe(5);
-expect(fibonacci(6)).toBe(8);
-expect(fibonacci(7)).toBe(13);
-expect(fibonacci(8)).toBe(21);
-expect(fibonacci(20)).toBe(6765);
+expect(fibonacci(1)).toEqual([1]);
+expect(fibonacci(2)).toEqual([1,1]);
+expect(fibonacci(3)).toEqual([1,1,2]);
+expect(fibonacci(4)).toEqual([1,1,2,3]);
+expect(fibonacci(5)).toEqual([1,1,2,3,5]);
+expect(fibonacci(6)).toEqual([1,1,2,3,5,8]);
+expect(fibonacci(7)).toEqual([1,1,2,3,5,8,13]);
+expect(fibonacci(8)).toEqual([1,1,2,3,5,8,13,21]);
 });
 });

src/algorithms/math/fibonacci/__test__/fibonacciNth.test.js

@@ -0,0 +1,15 @@
+importfibonacciNthfrom'../fibonacciNth';
+
+describe('fibonacciNth',()=>{
+it('should calculate fibonacci correctly',()=>{
+expect(fibonacciNth(1)).toBe(1);
+expect(fibonacciNth(2)).toBe(1);
+expect(fibonacciNth(3)).toBe(2);
+expect(fibonacciNth(4)).toBe(3);
+expect(fibonacciNth(5)).toBe(5);
+expect(fibonacciNth(6)).toBe(8);
+expect(fibonacciNth(7)).toBe(13);
+expect(fibonacciNth(8)).toBe(21);
+expect(fibonacciNth(20)).toBe(6765);
+});
+});

src/algorithms/math/fibonacci/fibonacci.js

@@ -1,26 +1,24 @@
-// Calculate fibonacci number at specific position using Dynamic Programming approach.
-exportdefaultfunctionfibonacci(numberPosition){
-if(numberPosition===1){
-return1;
-}
+// Return a fibonacci sequence as an array
+exportdefaultfunctionfibonacci(n){
+constfibSequence=[1];
+
+letcurrentValue=1;
+letpreviousValue=0;
 
-letiterationsCounter=numberPosition-1;
+if(n===1){
+returnfibSequence;
+}
 
-// Calculated fibonacci number.
-letfib=null;
-// Previous fibonacci number.
-letfibPrev=1;
-// Before previous fibonacci number.
-letfibPrevPrev=0;
+letiterationsCounter=n-1;
 
 while(iterationsCounter){
-// Calculate current value using two previous ones.
-fib=fibPrev+fibPrevPrev;
-// Shift previous values.
-fibPrevPrev=fibPrev;
-fibPrev=fib;
+currentValue+=previousValue;
+previousValue=(currentValue-previousValue);
+
+fibSequence.push(currentValue);
+
 iterationsCounter-=1;
 }
 
-returnfib;
+returnfibSequence;
 }

src/algorithms/math/fibonacci/fibonacciNth.js

@@ -0,0 +1,20 @@
+// Calculate fibonacci number at specific position using Dynamic Programming approach.
+exportdefaultfunctionfibonacciNth(n){
+letcurrentValue=1;
+letpreviousValue=0;
+
+if(n===1){
+return1;
+}
+
+letiterationsCounter=n-1;
+
+while(iterationsCounter){
+currentValue+=previousValue;
+previousValue=(currentValue-previousValue);
+
+iterationsCounter-=1;
+}
+
+returncurrentValue;
+}