题解 | #二叉树中的最大路径和#

/**
 * struct TreeNode {
 *	int val;
 *	struct TreeNode *left;
 *	struct TreeNode *right;
 * };
 */

class Solution {
public:
    /**
     * 
     * @param root TreeNode类 
     * @return int整型
     */
    int dfs(TreeNode* root,int &ret){
        if(!root) return 0;
        int l = dfs(root->left,ret),r = dfs(root->right,ret);
        int res = max(l + root->val,r + root->val);
        ret = max(ret,max(max(res,root->val),l+r+root->val));
        return max(res,root->val);
    }
    int maxPathSum(TreeNode* root) {
        // write code here
        int ret = INT_MIN;
        dfs(root,ret);
        return ret;
    }
};