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124 Binary Tree Maximum Path Sum

Given a binary tree, find the maximum path sum.

The path may start and end at any node in the tree.

For example:
Given the below binary tree,

       1
      / \
     2   3
Return 6.

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
int max;
private:
    int DFS(TreeNode *root)
    {
        int left , right , value;
        if(root == NULL)
            return 0;
        left = DFS(root->left);
        right = DFS(root->right);
        value = root->val;
        if(left>0)
            value += left;
        if(right>0)
            value += right;
        if(value > max)
            max = value;
        if(left>right && left>0)
            return root->val + left;
        if(left<right && right>0)
            return root->val + right;
        return root->val;
    }
public:
    int maxPathSum(TreeNode *root) {
        max = -1000000;
        DFS(root);
        return max;
    }
};

leetcode_124_Binary Tree Maximum Path Sum

标签：c++   leetcode   tree   dfs   

原文地址：http://blog.csdn.net/keyyuanxin/article/details/44197147