[LeetCode]530. Minimum Absolute Difference in BST

题目描述

思路

深搜
递归方式
固定最大右值的同时，不断更新当前值和左值
固定最小左值的同时，不断更新当前值和右值
计算差值同时维护一个最小值。

代码

#include <iostream>#include <algorithm>using namespace std;struct TreeNode {    int val;    TreeNode* left;    TreeNode* right;    TreeNode(int x): val(x), left(NULL), right(NULL){}};class Solution {public:    int getMinimumDifference(TreeNode* root) {        int res = INT_MAX;        dfs(root, NULL, NULL, res);        return res;    }private:    void dfs(TreeNode*root, TreeNode* minLeft, TreeNode* maxRight, int& res) {        if (root == NULL)            return;        dfs(root->left, minLeft, root, res);        dfs(root->right, root, maxRight, res);        if (minLeft)            res = min(res, root->val - minLeft->val);        if (maxRight)            res = min(res, maxRight->val - root->val);    }};int main() {    TreeNode* node1 = new TreeNode(236);    TreeNode* node2 = new TreeNode(104);    TreeNode* node3 = new TreeNode(701);    TreeNode* node4 = new TreeNode(227);    TreeNode* node5 = new TreeNode(911);    node1->left = node2;    node1->right = node3;    node2->right = node4;    node3->right = node5;    Solution s;    cout << s.getMinimumDifference(node1) << endl;    system("pause");    return 0;}