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// @Title: 另一个树的子树 (Subtree of Another Tree)
// @Author: 15816537946@163.com
// @Date: 2020-06-25 07:15:36
// @Runtime: 20 ms
// @Memory: 6.2 MB
/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */
 /*
func isSubtree(s *TreeNode, t *TreeNode) bool {
	if s == nil {
		return   false
	}
	return isSame(s,t)||  isSubtree(s.Left, t) || isSubtree(s.Right,t)
}

func isSame(s *TreeNode, t *TreeNode) bool {
	if s == nil {
		return t== nil
	}
	 if t == nil {
		return false
	}
	if t.Val != s.Val {
		return false
	}

	return isSame(s.Left,t.Left) && isSame(s.Right,t.Right)
}
*/


func isSubtree(s *TreeNode, t *TreeNode) bool {
	if s == nil {
		return false
	}

	return isSame(s, t) || isSubtree(s.Left, t) || isSubtree(s.Right, t)
}

func isSame(s *TreeNode, t *TreeNode) bool {
	if s == nil {
		return t == nil
	}
	if t == nil {
		return false
	}
	if s.Val != t.Val {
		return false
	}
	return isSame(s.Left, t.Left) && isSame(s.Right, t.Right)
}