Package g0601_0700.s0671_second_minimum_node_in_a_binary_tree

Class Solution

java.lang.Object

g0601_0700.s0671_second_minimum_node_in_a_binary_tree.Solution

public class Solution
extends Object

671 - Second Minimum Node In a Binary Tree.<p>Easy</p> <p>Given a non-empty special binary tree consisting of nodes with the non-negative value, where each node in this tree has exactly <code>two</code> or <code>zero</code> sub-node. If the node has two sub-nodes, then this node&rsquo;s value is the smaller value among its two sub-nodes. More formally, the property <code>root.val = min(root.left.val, root.right.val)</code> always holds.</p> <p>Given such a binary tree, you need to output the <strong>second minimum</strong> value in the set made of all the nodes&rsquo; value in the whole tree.</p> <p>If no such second minimum value exists, output -1 instead.</p> <p><strong>Example 1:</strong></p> <p><img src="https://assets.leetcode.com/uploads/2020/10/15/smbt1.jpg" alt="" /></p> <p><strong>Input:</strong> root = [2,2,5,null,null,5,7]</p> <p><strong>Output:</strong> 5</p> <p><strong>Explanation:</strong> The smallest value is 2, the second smallest value is 5.</p> <p><strong>Example 2:</strong></p> <p><img src="https://assets.leetcode.com/uploads/2020/10/15/smbt2.jpg" alt="" /></p> <p><strong>Input:</strong> root = [2,2,2]</p> <p><strong>Output:</strong> -1</p> <p><strong>Explanation:</strong> The smallest value is 2, but there isn&rsquo;t any second smallest value.</p> <p><strong>Constraints:</strong></p> <ul> <li>The number of nodes in the tree is in the range <code>[1, 25]</code>.</li> <li><code>1 <= Node.val <= 2³¹ - 1</code></li> <li><code>root.val == min(root.left.val, root.right.val)</code> for each internal node of the tree.</li> </ul>

Constructor Summary

Constructors

Constructor	Description
Solution()

Method Summary

Modifier and Type	Method	Description
int	findSecondMinimumValue(TreeNode root)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

Solution

public Solution()

Method Details

findSecondMinimumValue

public int findSecondMinimumValue(TreeNode root)