标签：pac www instead __init__ href rgb script line pretty
Given a non-empty special binary tree consisting of nodes with the non-negative value, where each node in this tree has exactly twoor zero sub-node. If the node has two sub-nodes, then this node‘s value is the smaller value among its two sub-nodes.
Given such a binary tree, you need to output the second minimum value in the set made of all the nodes‘ value in the whole tree.
If no such second minimum value exists, output -1 instead.
Example 1:
Input: 2 / 2 5 / 5 7 Output: 5 Explanation: The smallest value is 2, the second smallest value is 5.
Example 2:
Input: 2 / 2 2 Output: -1 Explanation: The smallest value is 2, but there isn‘t any second smallest value.
# Definition for a binary tree node.# class TreeNode(object):# def __init__(self, x):# self.val = x# self.left = None# self.right = Noneclass Solution(object):def findSecondMinimumValue(self, root):""":type root: TreeNode:rtype: int"""s = set()queue = [root]while queue and queue[0]:node = queue.pop(0)s.add(node.val)if node.left:queue.append(node.left)if node.right:queue.append(node.right)if len(s) < 2:return -1else:s.remove(min(s))return min(s)
671. Second Minimum Node In a Binary Tree 二叉树中第二小节点
标签：pac www instead __init__ href rgb script line pretty
原文地址：http://www.cnblogs.com/xiejunzhao/p/7501655.html
