algorithm/Week_02/id_102/leetcode_671_102.cpp at master · feixiangcode/algorithm · GitHub

37 lines (32 loc) · 998 Bytes

/**

* Definition for a binary tree node.

* struct TreeNode {

* int val;

* TreeNode *left;

* TreeNode *right;

* TreeNode(int x) : val(x), left(NULL), right(NULL) {}

* };

* Link: https://leetcode-cn.com/problems/second-minimum-node-in-a-binary-tree/comments/

class Solution {

long secondMinVal = LONG_MAX;

bool isRoot = true;

int rootVal;

public:

int findSecondMinimumValue(TreeNode* root) {

if (root == NULL) {

return -1;

}

if (isRoot) {

isRoot = false;

rootVal = root->val;

}

/* 寻找比root value大，但是比secondMinVal小的值 ß*/

if ((long)root->val > rootVal && (long)root->val < secondMinVal) {

secondMinVal = (long)root->val;

}

findSecondMinimumValue(root->left);

findSecondMinimumValue(root->right);

return secondMinVal != LONG_MAX ? secondMinVal : -1;

}

};

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