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| // @Title: 二叉树中第二小的节点 (Second Minimum Node In a Binary Tree)
// @Author: 15816537946@163.com
// @Date: 2019-11-25 10:23:06
// @Runtime: 0 ms
// @Memory: 1.9 MB
/**
* Definition for a binary tree node.
* type TreeNode struct {
* Val int
* Left *TreeNode
* Right *TreeNode
* }
*/
func findSecondMinimumValue(root *TreeNode) int {
max := 1<<63 - 1
hi := max
var helper func(*TreeNode, int)
helper = func(node *TreeNode, lo int) {
if node == nil {
return
}
if lo < node.Val && node.Val < hi {
hi = node.Val
}
helper(node.Left, lo)
helper(node.Right, lo)
}
helper(root, root.Val)
if max == hi {
return -1
}
return hi
}
|