python求斐波那契数列前n项和
时间: 2023-11-18 12:04:19 浏览: 106
可以使用递归或循环来求解斐波那契数列前n项和。
使用递归:
```python
def fibonacci(n):
if n <= 1:
return n
else:
return (fibonacci(n-1) + fibonacci(n-2))
n = int(input("请输入斐波那契数列项数:"))
if n <= 0:
print("输入有误!")
else:
sum = 0
for i in range(n):
sum += fibonacci(i)
print("斐波那契数列前", n, "项的和为:", sum)
```
使用循环:
```python
n = int(input("请输入斐波那契数列项数:"))
if n <= 0:
print("输入有误!")
else:
a, b = 0, 1
sum = 0
for i in range(n):
sum += a
a, b = b, a+b
print("斐波那契数列前", n, "项的和为:", sum)
```
相关问题
Python求斐波那契数列前n项和
以下是求斐波那契数列前n项和的Python代码:
```python
def fibonacci_sum(n):
if n <= 0:
return 0
elif n == 1:
return 1
else:
fib1 = 0
fib2 = 1
sum = 1
for i in range(2, n+1):
fib = fib1 + fib2
sum += fib
fib1 = fib2
fib2 = fib
return sum
n = int(input("请输入正整数n:"))
print("斐波那契数列前", n, "项的和为:", fibonacci_sum(n))
```
运行结果:
```
请输入正整数n:10
斐波那契数列前 10 项的和为: 143
```
Python 求斐波那契数列前n项
在Python中,计算斐波那契数列(Fibonacci sequence)前n项通常通过递归或循环的方式实现。以下是两种常见的方法:
**方法一:使用循环(迭代法)**
```python
def fibonacci_iterative(n):
fib_sequence = [0, 1]
while len(fib_sequence) < n:
fib_sequence.append(fib_sequence[-1] + fib_sequence[-2])
return fib_sequence[:n]
# 使用示例
n = 10
print(fibonacci_iterative(n))
```
**方法二:使用递归(递归法,但效率较低,不适合大数值)**
```python
def fibonacci_recursive(n):
if n <= 0:
return []
elif n == 1:
return [0]
elif n == 2:
return [0, 1]
else:
fib_sequence = fibonacci_recursive(n - 1)
fib_sequence.append(fib_sequence[-1] + fib_sequence[-2])
return fib_sequence
# 使用示例
n = 10
print(fibonacci_recursive(n))
```
这两种方法都能得到前n项斐波那契数列,但是由于递归的效率较低,对于非常大的n值可能会导致性能问题。
阅读全文