*leetcode #124 in cpp

最新推荐文章于 2025-08-17 23:28:34 发布

xiaolienahu

最新推荐文章于 2025-08-17 23:28:34 发布

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分类专栏： interview 文章标签： cpp leetcode

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探讨了在二叉树中寻找最大路径和的问题，并提供了一种递归解决方案。路径被定义为从任意节点到任意节点的一系列连接，不一定要通过根节点。

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Given a binary tree, find the maximum path sum.

For this problem, a path is defined as any sequence of nodes from some starting node to any node in the tree along the parent-child connections. The path does not need to go through the root.

For example:
Given the below binary tree,

       1
      / \
     2   3

Return 6.

Solution:

This question is pretty hard. I did not figure it out until I searched for solution online.

Code:

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    int maxPathSum(TreeNode* root) {
        int maxx = INT_MIN;
        findMaxPathSum(root, maxx);
        return maxx; 
    }
    int findMaxPathSum(TreeNode *node,int &maxx){ //this function returns the max path sum from node to its successors i.  
        if(!node) return 0;
        int left = findMaxPathSum(node->left,maxx); 
        int right = findMaxPathSum(node->right,maxx);
        int temp = max(max(node->val, node->val + left),node->val + right);
        maxx = max(max(temp,node->val+left + right), maxx);//record the max sum at node, by comparing max path sum that starts at node, and max path sum that goes from left child to node to right child. 
        return temp;
    }
    
    
};