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)
思路:将B与A,A的左子树,A的右子树分别进行判断,如果元素不相等返回 false ,运用递归直到A子树为空此时返回 false
/**
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(root1 == null || root2 == null)return false;
return isHubTree(root1,root2)||HasSubtree(root1.right,root2)||HasSubtree(root1.left,root2);
}
public boolean isHubTree(TreeNode root1,TreeNode root2){
if(root1 == null && root2 == null)return true;
if(root1 == null)return false;
if(root2 == null)return true;
if(root1.val != root2.val)return false;
return isHubTree(root1.left,root2.left) && isHubTree(root1.right,root2.right);
}
}