题目描述：
一般思路：
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
public boolean isUnivalTree(TreeNode root) {
if (root == null) {
return true;
}
Queue<TreeNode> tem = new LinkedList<>();
tem.offer(root);
while (!tem.isEmpty()) {
int size = tem.size();
for (int i = 0; i < size; i++) {
TreeNode sNode = tem.poll();
if(root.val != sNode.val){
return false;
}
if(sNode.left != null){
tem.offer(sNode.left);
}
if(sNode.right != null){
tem.offer(sNode.right);
}
}
}
return true;
}
}
使用递归来进行
递归还是不是很熟悉啊，哎
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
public boolean isUnivalTree(TreeNode root) {
if(root == null){
return true;
}
return is(root.left,root.val) && is(root.right,root.val);
}
public boolean is(TreeNode root,int val){
if(root == null){
return true;
}
if(root.val != val){
return false;
}
return is(root.left,val) && is(root.right,val);
}
}