Problem 100: Same Tree
思路
分治递归的思路非常重要。
/**
* 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 isSameTree(TreeNode p, TreeNode q) {
if (p == null && q == null) {
return true;
}
if (p != null && q != null) {
return p.val == q.val && isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
}
return false;
}
}
易错点
在判断的过程中,要用递归的思想来判断剩下的树结构是否相等
if (p != null && q != null) { return p.val == q.val && isSameTree(p.left, q.left) && isSameTree(p.right, q.right); }
当时错写成了,
return p.val == q.val && p.left == q.left && p.right == q.right;
这样做实际上判断的是 root 以及 root 的左右是否相等。
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