You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
36 lines
830 B
36 lines
830 B
"""
|
|
File: climbing_stairs_dfs_mem.py
|
|
Created Time: 2023-06-30
|
|
Author: krahets (krahets@163.com)
|
|
"""
|
|
|
|
|
|
def dfs(i: int, mem: list[int]) -> int:
|
|
"""记忆化搜索"""
|
|
# 已知 dp[1] 和 dp[2] ,返回之
|
|
if i == 1 or i == 2:
|
|
return i
|
|
# 若存在记录 dp[i] ,则直接返回之
|
|
if mem[i] != -1:
|
|
return mem[i]
|
|
# dp[i] = dp[i-1] + dp[i-2]
|
|
count = dfs(i - 1, mem) + dfs(i - 2, mem)
|
|
# 记录 dp[i]
|
|
mem[i] = count
|
|
return count
|
|
|
|
|
|
def climbing_stairs_dfs_mem(n: int) -> int:
|
|
"""爬楼梯:记忆化搜索"""
|
|
# mem[i] 记录爬到第 i 阶的方案总数,-1 代表无记录
|
|
mem = [-1] * (n + 1)
|
|
return dfs(n, mem)
|
|
|
|
|
|
"""Driver Code"""
|
|
if __name__ == "__main__":
|
|
n = 9
|
|
|
|
res = climbing_stairs_dfs_mem(n)
|
|
print(f"爬 {n} 阶楼梯共有 {res} 种方案")
|