题解 | #统计每个月兔子的总数#

#这是一个经典递归问题，也可以用动态规划算法求解
#1.动态规划
def rabbit_population(n):
    if n == 1 or n == 2:
        return 1
    junior = 1
    adults = 1
    for _ in range(3,n+1):
        new_rabbit = adults
        adults,junior = new_rabbit + junior,new_rabbit
    return adults

#2.递归算法
def fabonacci(n):
    if n == 1 or n == 2:
        return 1
    else:
        return fabonacci(n-1)+fabonacci(n-2)

if __name__=='__main__':
    n = int(input())
    print(fabonacci(n))
#共有两种算法，用递归就比较容易实现也比较好想出来；用动态规划迭代，range(3,n+1),初始化junior,adults取值1，每一次迭代更新junior和adults分别为new_rabbit和new_rabbit+junior,其中new_rabbit = adults