[Python手撕]不同的二叉搜索树
class Solution:
def numTrees(self, n: int) -> int:
dp = [0]*(n+1)
dp[0] = 1
dp[1] = 1
for i in range(2,n+1):
for j in range(i):
dp[i] += dp[j]*dp[i-1-j]
return dp[-1]