剑指 offer 树的子结构

/*
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;
        }
        bool left,right;
        
        left =  helper(pRoot1 -> left,pRoot2 -> left);
        right =  helper(pRoot1 -> right,pRoot2 -> right);
        
        return left && right;
        
    }
  
    bool HasSubtree(TreeNode* pRoot1, TreeNode* pRoot2) {
        if(pRoot1 == nullptr || pRoot2 == nullptr){
            return false;
        }
        return helper(pRoot1,pRoot2) || helper(pRoot1 -> left,pRoot2) || helper(pRoot1 -> right,pRoot2);        
    }
};