刷题--树的子结构

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）
 
struct TreeNode {int val;struct TreeNode *left;struct TreeNode *right;TreeNode(int x) :val(x), left(NULL), right(NULL) {}};bool doestree1hastree2(TreeNode* pRoot1, TreeNode* pRoot2){if (pRoot2 == NULL)return true;if (pRoot1 == NULL)return false;if (pRoot1->val != pRoot2->val)return false;//当头结点一样的时候，再判断树1和树2左子树和右子树是否都相等。只有都相等时，才返回真，否则返回假return doestree1hastree2(pRoot1->left, pRoot2->left) && doestree1hastree2(pRoot1->right, pRoot2->right);}bool HasSubtree(TreeNode* pRoot1, TreeNode* pRoot2){bool res = false;if (pRoot1 != NULL&&pRoot2 != NULL){if (pRoot1->val == pRoot2->val)//若有相同的结点，继续判断是否2在1中res = doestree1hastree2(pRoot1, pRoot2);if (!res){res=HasSubtree(pRoot1->left, pRoot2);}if (!res)//若左子树中没有找到和树2一致的子树，则在右子树中找{res = HasSubtree(pRoot1->right, pRoot2);}}return res;}