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。)
/**
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) {
boolean result=false;
if(root1!=null && root2!=null){
//A,B树当前结点相同的话,就继续比较A,B数下个结点
if(root1.val==root2.val)
result=DoesRoot1HaveRoot2(root1,root2);
//A,B树当前结点不相同的话,就继续比较A左结点与B树当前结点
if(!result)
result=HasSubtree(root1.left,root2);
//A左结点与B树当前结点不相同的话,就继续比较A右结点与B树当前结点
if(!result)
result=HasSubtree(root1.right,root2);
}
return result;
}
/**
*A,B树当前结点相同的前提下,继续比较A,B树下个结点
*
/
private boolean DoesRoot1HaveRoot2(TreeNode root1,TreeNode root2) {
if(root2==null)
return true;
if(root1==null)
return false;
if(root1.val!=root2.val)
return false;
return DoesRoot1HaveRoot2(root1.left,root2.left)
&&DoesRoot1HaveRoot2(root1.right,root2.right);
}
}
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