/** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode() : val(0), left(nullptr), right(nullptr) {} * TreeNode(int x) : val(x), left(nullptr), right(nullptr) {} * TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {} * }; */ class Solution { public: int maxLength=0; void solve(TreeNode* root,int dir,int currLength){ if(!root) return; maxLength=max(maxLength,currLength); solve(root->left,0,dir?currLength+1:1); solve(root->right,1,dir?1:currLength+1); } int longestZigZag(TreeNode* root) { solve(root,0,0); solve(root,1,0); return maxLength; } };