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SameTree.java
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SameTree.java
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/*
想法在于p, q 同时为空
和只有一个为空的情况
然后想到左右子树是否相等
*/
public boolean isSameTree(TreeNode p, TreeNode q) {
if(p == null && q == null) return true;
if(p == null || q == null) return false;
return p.val == q.val && isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
}
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public boolean isSymmetric(TreeNode root) {
if(root == null) return true;
return isSame(root.left, root.right);
}
public boolean isSame(TreeNode left, TreeNode right){
if(left == null && right == null) return true;
if(left == null || right == null) return false;
return left.val == right.val && isSame(left.left, right.right)
&& isSame(left.right, right.left);
}
}