语言:Python 描述:使用递归实现 class Solution: # @return an integer def numTrees(self, n): : elif n == : else: part_1 = self.numTrees(n-) * part_2 = ,n-): part_left = self.numTrees(i) part_right = self.numTrees(n - - i) part_2 += part_left * part_right return p…

语言:Python 描述:使用递归实现 # Definition for a binary tree node # class TreeNode: # def __init__(self, x): # self.val = x # self.left = None # self.right = None class Solution: # @param p, a tree node # @param q, a tree node # @return a boolean def isSameTre…

对于数字n(大于1).从1到n有多少种binary search tree(BST序列)?当n=3时,BST序列为: 1         3     3    2     1     \         /     /      / \      \     3      2    1    1  3     2     /       /       \                  \   2      1         2                3共5种. 分析: N=1时,…

描述: 使用了递归,有些计算是重复的,用了额外的空间,Version 1是m*n Bonus:一共走了m+n步,例如 m = 2, n = 3 [#, @, @, #, @],所以抽象成数学问题,解是C(m + n, m) 代码: class Solution: # @return an integer def __init__(self): self.record = {} def uniquePaths(self, m, n): if m == 0 or n == 0: return 0 i…

描述:递归调用,getMax返回 [节点值,经过节点左子节点的最大值,经过节点右节点的最大值],每次递归同时查看是否存在不经过节点的值大于max. 代码:待优化 def getLargeNode(self, a, b): if a and b: return max(a, b) elif a and not b: return a elif not a and b: return b else: tmp = None def getMax(self, node): if node is None…

ZOJ Problem Set - 1097 Code the Tree Time Limit: 2 Seconds      Memory Limit: 65536 KB A tree (i.e. a connected graph without cycles) with vertices numbered by the integers 1, 2, ..., n is given. The "Prufer" code of such a tree is built as foll…

Code the Tree Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 2350   Accepted: 906 Description A tree (i.e. a connected graph without cycles) with vertices numbered by the integers 1, 2, ..., n is given. The "Prufer" code of such a…

Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 2292   Accepted: 878 Description A tree (i.e. a connected graph without cycles) with vertices numbered by the integers 1, 2, ..., n is given. The "Prufer" code of such a tree is built…

Code the Tree Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 2259   Accepted: 859 Description A tree (i.e. a connected graph without cycles) with vertices numbered by the integers 1, 2, ..., n is given. The "Prufer" code of such a…

G.Code the Tree Time Limit: 2 Sec  Memory Limit: 128 MB Submit: 35  Solved: 18 [Submit][Status][Web Board] Description A tree (i.e. a connected graph without cycles) with vertices numbered by the integers 1, 2, ..., n is given. The "Prufer" code…