Given a binary tree, find the length of the longest path where each node in the path has the same value. This path may or may not pass through the root.
Note: The length of path between two nodes is represented by the number of edges between them.
Example 1:
Input:
5
/ \
4 5
/ \ \
1 1 5
Output:
2
Example 2:
Input:
1
/ \
4 5
/ \ \
4 4 5
Output:
2
Note: The given binary tree has not more than 10000 nodes. The height of the tree is not more than 1000.
class Solution {
public:
int longestUnivaluePath(TreeNode* root) {
int lup = ;
if (root) dfs(root, lup);
return lup;
}
private:
int dfs(TreeNode* node, int& lup) {
int l = node->left ? dfs(node->left, lup) : ;
int r = node->right ? dfs(node->right, lup) : ;
int resl = node->left && node->left->val == node->val ? l + : ;
int resr = node->right && node->right->val == node->val ? r + : ;
lup = max(lup, resl + resr);
return max(resl, resr);
}
};