题目
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.
解题思路
如果t是s的子树，则s必有一个子树和t相等。因此遍历s，所有s的子树和t相比，如果有相等的就说明t是s的子树
注意
找到子树后就不再进行遍历
if subTree {
return
}
代码
/**
* Definition for a binary tree node.
* type TreeNode struct {
* Val int
* Left *TreeNode
* Right *TreeNode
* }
*/
func isTreeEqual(s *TreeNode, t *TreeNode) bool {
if nil == s && nil == t {
return true
} else if nil != s && nil == t {
return false
} else if nil == s && nil != t {
return false
}
if s.Val != t.Val {
return false
}
if !isTreeEqual(s.Left, t.Left) {
return false
}
if !isTreeEqual(s.Right, t.Right) {
return false
}
return true
}
var subTree bool
func travelTree(s *TreeNode, t *TreeNode) {
//already find subtree
if subTree {
return
}
if nil == s {
return
}
if isTreeEqual(s, t) {
subTree = true
return
}
travelTree(s.Left, t)
travelTree(s.Right, t)
}
func isSubtree(s *TreeNode, t *TreeNode) bool {
subTree = false
travelTree(s, t)
return subTree
}
