剑指offer 17：树的子结构

树的子结构

 

#include <iostream>

using namespace std;

//树的子结构
struct TreeNode
{
    int val;
    TreeNode *left;
    TreeNode *right;

    TreeNode(int x)
        : val(x), left(NULL), right(NULL)
    {

    }
};


class Solution
{
public:
    bool HasSubtree(TreeNode* parent, TreeNode* child) {
        if (child == NULL || parent == NULL) {
            return false;
        }

        bool result;

        if (parent->val == child->val) {
            result = DoesParentHaveChild(parent, child);
        }//父树节点与子数根节点相同，直接开始判断

        if (result != true) {
            return HasSubtree(parent->left, child) || HasSubtree(parent->left, child);
        }

        else {
            return true;
        }


    }

    bool DoesParentHaveChild(TreeNode *parent , TreeNode *child) {
        if (child == NULL) {
            return true;//子数空，必是子数
        }
        else if (parent == NULL) {
            return false;
        }
		//两个节点的值不想等，必然不是父子关系
        if (parent->val != child->val) {
            return false;
        }

        else {//否则相等，递归判断左子数和右子树的对应节点是否相等
            return DoesParentHaveChild(parent->left,child->left)
                    && DoesParentHaveChild(parent->right, child->right);
        }
    }
};

int main()
{
    cout << "test" << endl;

    return 0;
}