algorithm/Week_02/id_100/LeetCode_671_100.java at master · algorithm001/algorithm · GitHub

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/**

* Definition for a binary tree node.

* public class TreeNode {

* int val;

* TreeNode left;

* TreeNode right;

* TreeNode(int x) { val = x; }

* }

class Solution {

public int findSecondMinimumValue(TreeNode root) {

return traversal(root, root.val);

}

private static int traversal(TreeNode root, int rootVal) {

if (root == null) {

return -1;

}

if (root.val > rootVal) {

return root.val;

}

int l = traversal(root.left, rootVal); // 遍历左节点值是否有大于根节点的值 3

System.out.println("left ----> " + l);

int r = traversal(root.right, rootVal); // 遍历右节点值是否有大于根节点的值 7

System.out.println("right --->" + r);

// 如果左右节点都比跟节点大的话，取最小的

if (l >= 0 && r >= 0) {

return Math.min(l, r);

}

// 否则取最大的

return Math.max(l, r);

}

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