我写了一个代码来判断小二叉树t1是否是t2的子树。我应该得到true
作为结果,但我得到相反的结果。
这是我的代码:
class Node {
int val;
Node left, right;
public Node(int v) {
val = v;
left = right = null;
}
}
public class BT {
Node root;
public BT() {
root = null;
}
public boolean containsTree(Node t1, Node t2) {
StringBuilder s1 = new StringBuilder();
StringBuilder s2 = new StringBuilder();
getOrderString(t1, s1);
getOrderString(t2, s2);
return s1.indexOf(s2.toString()) != -1;
}
public void getOrderString(Node t, StringBuilder s) {
if (t == null) {
s.append("X");
return;
}
s.append(t.val);
getOrderString(t.left, s);
getOrderString(t.right, s);
}
public static void main(String[] args) {
BT bt = new BT();
bt.root = new Node(10);
bt.root.left = new Node(12);
bt.root.right = new Node(15);
bt.root.left.left = new Node(25);
bt.root.left.right = new Node(30);
bt.root.right.left = new Node(36);
BT bt2 = new BT();
bt2.root = new Node(10);
bt2.root.left = new Node(12);
bt2.root.right = new Node(15);
bt2.root.left.left = new Node(25);
System.out.println(bt.containsTree(bt.root, bt2.root));
}
}
有人可以向我解释为什么我变得虚假吗?
您用于构造树的API很难阅读。如果定义了构造函数:
public Node(int v, Node left, Node right)
然后您可以将树声明为:
bt.root = new Node(
10,
new Node(
12,
new Node(25, null, null),
new Node(30, null, null)),
new Node(
25,
new Node(36, null, null),
null));
bt2.root = new Node(
10,
new Node(
12,
new Node(25, null, null),
null)),
new Node(15, null, null));
类似,我认为很容易看到第二个不是第一个的子树: