LeetCode-572. Subtree of Another Tree (JAVA)子树

572. Subtree of Another Tree

Given two non-empty binary trees s and t, check whether tree t has exactly the same structure and node values with a subtree of s. A subtree of s is a tree consists of a node in s and all of this node's descendants. The tree s could also be considered as a subtree of itself.

Example 1:
Given tree s:

     3    / \   4   5  / \ 1   2

Given tree t:

   4   / \ 1   2

Return true, because t has the same structure and node values with a subtree of s.

Example 2:
Given tree s:

     3    / \   4   5  / \ 1   2    /   0

Given tree t:

   4  / \ 1   2

Return false.

判断一颗二叉树t是否是一颗二叉树s的 子树.

public boolean isSubtree(TreeNode s, TreeNode t) {if (s == null)return false;if (isSame(s, t))return true;return isSubtree(s.left, t) || isSubtree(s.right, t);}private boolean isSame(TreeNode s, TreeNode t) {if (s == null && t == null)return true;if (s == null || t == null)return false;if (s.val != t.val)return false;return isSame(s.left, t.left) && isSame(s.right, t.right);}