剑指Offer：17-树的子结构

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

实现

/*
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
    TreeNode(int x) :
            val(x), left(NULL), right(NULL) {
    }
};*/
class Solution {
public:
    bool HasSubtree(TreeNode* pRoot1, TreeNode* pRoot2)
    {
        if(!pRoot1 || !pRoot2)
            return false;
        bool result = false;
        if(pRoot1->val == pRoot2->val)
            result = IsSameTree(pRoot1, pRoot2);
        if(!result)
            result = HasSubtree(pRoot1->left, pRoot2) || HasSubtree(pRoot1->right, pRoot2);
        return result;
    }
private:
    bool IsSameTree(TreeNode* pRoot1, TreeNode* pRoot2)
    {
        if(!pRoot2)
            return true;
        if(!pRoot1)
            return false;
        if(pRoot1->val == pRoot2->val)
            return IsSameTree(pRoot1->left, pRoot2->left) && IsSameTree(pRoot1->right, pRoot2->right);
        else
            return false;
    }
};