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题目描述
输入两棵二叉树A,B,判断B是不是A的子结构。(ps:我们约定空树不是任意一个树的子结构)
题目链接:https://www.nowcoder.com/practice/6e196c44c7004d15b1610b9afca8bd88
解题思路
递归A树的左右子树,当遇到根节点同B树相同的,进行判断
public class Solution {
public boolean HasSubtree(TreeNode root1, TreeNode root2) {
if (root1 == null || root2 == null) return false;
boolean result = false;
if (root1.val == root2.val) {
result = check(root1, root2);
}
if (!result) {
result = HasSubtree(root1.left, root2);
}
if (!result) {
result = HasSubtree(root1.right, root2);
}
return result;
}
private boolean check(TreeNode node1, TreeNode node2) {
if (node2 == null) return true;
if (node1 == null) return false;
if (node1.val != node2.val) return false;
boolean result = true;
result = check(node1.left, node2.left) && check(node1.right, node2.right);
return result;
}
}