[Leetcode] Binary Tree Maximum Path Sum

最新推荐文章于 2024-03-25 21:39:45 发布

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本文介绍了一个解决二叉树最大路径和问题的算法实现。通过递归方式计算包含根节点的最大路径和，并更新全局最大值。最终返回二叉树中的最大路径和。

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    int maxPathSum(TreeNode *root) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if (!root) return 0;
        int maxSoFar = root->val;
        int temp = maxContainRoot(root, maxSoFar);
        return maxSoFar;
    }
    
    int maxContainRoot(TreeNode* n, int& maxSoFar)
    {
        if (!n) return 0;
        
        int leftMax = maxContainRoot(n->left, maxSoFar);
        int rightMax = maxContainRoot(n->right, maxSoFar);
        
        int result = n->val;
        int maxPath = n->val;
        int longerLeg = max(leftMax, rightMax);
        
        result = max(result, result + longerLeg);
        
        maxPath = max(maxPath, maxPath + leftMax);
        maxPath = max(maxPath, maxPath + rightMax);
        maxSoFar = max(maxSoFar, maxPath);
        
        return result;
    }
};