标签：logs etc log self stack style blog bsp span
思路1： 递归，如果 p = q, 那么判段 sameTree(p.left)==sameTree(q.left) and sameTree(p.right) = sameTree(q.right)
1 class Solution(object): 2 def isSameTree(self, p, q): 3 """ 4 :type p: TreeNode 5 :type q: TreeNode 6 :rtype: bool 7 """ 8 if not p and not q: 9 return True 10 11 if p and q: 12 if p.val == q.val: 13 return self.isSameTree(p.left, q.left) and self.isSameTree(p.right, q.right) 14 else: 15 return False 16 17 return False
思路二： 如果两个树相同，说明按照一定的方式遍历这两个树，应该得到一样的结果。这里用的方法是使用stack来实现先序遍历（pre-order）。注意pre-order遍历时是，root -> root.left -> root.right。所以push进stack的时候应该先push root.right再push root.left。
1 class Solution(object): 2 def isSameTree(self, p, q): 3 """ 4 :type p: TreeNode 5 :type q: TreeNode 6 :rtype: bool 7 """ 8 if p == None and q == None: 9 return True 10 11 stack = [(p, q)] 12 13 while stack: 14 l, r = stack.pop() 15 16 if l == None and r == None: 17 continue 18 elif l and r and l.val == r.val: 19 20 stack.append((l.right, r.right)) 21 22 stack.append((l.left, r.left)) 23 else: 24 return False 25 26 return True
标签：logs etc log self stack style blog bsp span
原文地址：http://www.cnblogs.com/lettuan/p/6349026.html
