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）
注意子结构和子树的区别
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| public boolean HasSubtree(TreeNode root1, TreeNode root2) {
if (root2 == null) {
return false;
}
List<TreeNode> treeNodeList = getNode(root2.val, root1);
for (TreeNode treeNode : treeNodeList) {
if (judgeTree(treeNode, root2)) {
return true;
}
}
return false;
}
boolean judgeTree(TreeNode r1, TreeNode r2) {
if (r2 == null) {
return true;
}
if (r1 == null) {
return false;
}
if (r1.val != r2.val) {
return false;
}
return judgeTree(r1.left, r2.left) && judgeTree(r1.right, r2.right);
}
List<TreeNode> getNode(int var, TreeNode root) {
List<TreeNode> ans = new ArrayList<>();
Stack<TreeNode> stack = new Stack<>();
if (root != null) {
stack.push(root);
}
while (!stack.empty()) {
TreeNode tmp = stack.pop();
if (tmp.val == var) {
ans.add(tmp);
}
if (tmp.left != null) {
stack.push(tmp.left);
}
if (tmp.right != null) {
stack.push(tmp.right);
}
}
return ans;
}
|