tribonacci.py

# Solucao recursiva 
def trib_tail (result, current, n): 
    # print(str(result), current, n)
    result.append( result[current-1] + result[current-2] + result[current-3] )
    if current < n:
        trib_tail(result, current + 1, n)
    return result

def tribonacci(signature,n):
    return signature[:n] if n-1 <3 else trib_tail(signature[:], 3, n-1)


# solucao iterativa
def tribonacci(signature,n):
    if n-1 <3:
       return signature[:n] 
    result = signature[:]
    for current in range(3,n):
        result.append( result[current-1] + result[current-2] + result[current-3] )
    return result


Test.describe("Basic tests")
Test.assert_equals(tribonacci([1,1,1],0),[])
Test.assert_equals(tribonacci([1,1,1],10),[1,1,1,3,5,9,17,31,57,105])
Test.assert_equals(tribonacci([0,0,1],10),[0,0,1,1,2,4,7,13,24,44])
Test.assert_equals(tribonacci([0,1,1],10),[0,1,1,2,4,7,13,24,44,81])
Test.assert_equals(tribonacci([1,0,0],10),[1,0,0,1,1,2,4,7,13,24])
Test.assert_equals(tribonacci([0,0,0],10),[0,0,0,0,0,0,0,0,0,0])
Test.assert_equals(tribonacci([1,2,3],10),[1,2,3,6,11,20,37,68,125,230])
Test.assert_equals(tribonacci([3,2,1],10),[3,2,1,6,9,16,31,56,103,190])
Test.assert_equals(tribonacci([1,1,1],1),[1])
Test.assert_equals(tribonacci([300,200,100],0),[])
Test.assert_equals(tribonacci([0.5,0.5,0.5],30),[0.5,0.5,0.5,1.5,2.5,4.5,8.5,15.5,28.5,52.5,96.5,177.5,326.5,600.5,1104.5,2031.5,3736.5,6872.5,12640.5,23249.5,42762.5,78652.5,144664.5,266079.5,489396.5,900140.5,1655616.5,3045153.5,5600910.5,10301680.5])