二叉树A、B,判断B是不是A的子树
代码如下
public class TreeNode {
int val = 0;
TreeNode left = null;
TreeNode right = null;
public TreeNode(int val) {
this.val = val;
}
}
public class Solution {
public boolean HasSubtree(TreeNode root1,TreeNode root2) {
if(root2 == null || root1 == null) return false;
return ifSub(root1,root2) ||
HasSubtree(root1.left,root2) ||
HasSubtree(root1.right,root2);
}
public boolean ifSub(TreeNode root1,TreeNode root2){
if(root2 == null) return true;
if(root1 == null) return false;//此时root2不为null,顺序不可变
if(root1.val == root2.val)
return ifSub(root1.left,root2.left) && ifSub(root1.right,root2.right);
else return false;
}
}