題目：
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\5

Longest consecutive sequence path is 3-4-5, so return 3.

2\3/ 2 / 1

Longest consecutive sequence path is 2-3,not3-2-1, so return 2.

解答：
分治，一種不帶返回值，但需要用全局變量，一種帶返回值，不用全局變量：
1.

//有全局變量private int max = 0;public void Helper(TreeNode root, int target, int count) {if (root == null) return;if (root.val == target) {count++;} else {count = 1;}max = Math.max(max, count);Helper(root.left, root.val + 1, count);Helper(root.right, root.val + 1, count);}public int longestConsecutive(TreeNode root) {if (root == null) return 0;Helper(root, root.val + 1, 1);return max;}

2.

public int Helper(TreeNode root, int target, int count) {if (root == null) return 1;count = root.val == target ? count + 1 : 1;int left = Helper(root.left, root.val + 1, count);int right = Helper(root.right, root.val + 1, count);return Math.max(Math.max(left, right), count); }public int longestConsecutive(TreeNode root) {if (root == null) return 0;return Math.max(Helper(root.left, root.val + 1, 1), Helper(root.right, root.val + 1, 1)); }

總結

以上是生活随笔為你收集整理的298. Binary Tree Longest Consecutive Sequence的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。