16 树的子结构(这题多复习)

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