[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):
count = 0
for left in range(0,i):
count += (dp[left]*dp[i-left-1])
dp[i] = count
return dp[-1]