687. Longest Univalue Path
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.
题目含义：找出二叉树中，最长的链路长度（由相同值构成的链路，可以不包含根节点）
1 private int sameNodeValue(TreeNode node, int[] res) { 2 int l = node.left != null ? sameNodeValue(node.left, res) : 0; 3 int r = node.right != null ? sameNodeValue(node.right, res) : 0; 4 int resl = node.left != null && node.left.val == node.val ? l + 1 : 0; 5 int resr = node.right != null && node.right.val == node.val ? r + 1 : 0; 6 res[0] = Math.max(res[0], resl + resr); 7 return Math.max(resl, resr); 8 } 9 10 public int longestUnivaluePath(TreeNode root) { 11 int[] res = new int[1]; 12 if (root != null) sameNodeValue(root, res); 13 return res[0]; 14 }
