Leetcode 298. Binary Tree Longest Consecutive Sequence (Medium) (cpp)

Leetcode 298. Binary Tree Longest Consecutive Sequence (Medium) (cpp)

Tag: Tree

Difficulty: Medium

/*298. Binary Tree Longest Consecutive Sequence (Medium)Given a binary tree, find the length of the longest consecutive sequence path.The path refers to any sequence of nodes from some starting node to any node in the tree along the parent-child connections. The longest consecutive path need to be from parent to child (cannot be the reverse).For example,1\3/ \2   4\5Longest consecutive sequence path is 3-4-5, so return 3.2\3/2/1Longest consecutive sequence path is 2-3,not3-2-1, so return 2.*//*** 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 longestConsecutive(TreeNode* root) {if (root == NULL) {return 0;}int res = 0;longestConsecutive(root, res, 0, root->val);return res;}private:void longestConsecutive(TreeNode* root, int& res, int cur, int tar) {if (root == NULL) {return;}if (root->val == tar) {cur++;}else {cur = 1;}res = max(res, cur);longestConsecutive(root->left, res, cur, root->val + 1);longestConsecutive(root->right, res, cur, root->val + 1);}};