python动态规划算法实例详解

# _*_coding:utf-8_*_
def fibnacci(n):
  if n == 1 or n == 2:
    return 1
  else:
    return fibnacci(n - 1) + fibnacci(n - 2)
 print(fibnacci(10)) # 55

f(1) = 1
f(2) = 1
f(3) = f(1) + f(2) = 1+ 1 = 2
f(4) = f(3) + f(2) = 2 + 1 = 3
...
f(n) = f(n-1) + f(n-2)

class Solution:
  def climbStairs(self, n: int) -> int:
    num_list = [0,1,2]
    if n==1:
      return num_list[1]
    elif n==2:
      return num_list[2]
    else:
      for i in range(3,n+1):
        num_list.append(num_list[i-1]+num_list[i-2])
    print(num_list)
    return num_list[n]

obj = Solution()
result = obj.climbStairs(10)
print(result)

class Solution:
  def climbStairs(self, n: int) -> int:
    a,b,c = 0,1,2
    if n == 1:
      return b
    if n == 2:
      return c
    while n>0:
      c = a + b
      a,b = b,c
      n -= 1
    return c
obj = Solution()
result = obj.climbStairs(8)