Path Sum leetcode C++

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.

For example:
Given the below binary tree and sum = 22,

              5             / \            4   8           /   / \          11  13  4         /  \      \        7    2      1

return true, as there exist a root-to-leaf path 5->4->11->2 which sum is 22.

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {  
public:  
    int depthSum=0;  
   // int targetSum;  
    bool depthSearch(TreeNode* root,int targetSum)  
    {  
        if(root)  
        {  
            if(root->right == NULL && root->left == NULL)  
            {  
                if(depthSum + root->val == targetSum)    return true;  
                else    return false;  
            }  
            depthSum += root->val;  
            bool res1 = depthSearch(root->left,targetSum);  
            bool res2 = depthSearch(root->right,targetSum);  
            depthSum -= root->val;  
            return res1||res2;  
        }  
        return false;  
    }  
    bool hasPathSum(TreeNode *root, int sum) { 
        depthSum = 0;  
       // targetSum = sum;  
        return depthSearch(root,sum);  
    }  
};