LeetCode Path Sum

/**

 * Definition for binary tree

 * struct TreeNode {

 *     int val;

 *     TreeNode *left;

 *     TreeNode *right;

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

 * };

 */

class Solution {

public:

    bool hasPathSum(TreeNode *root, int sum) {

        return dfs(root, 0, sum);

    }

    

    bool dfs(TreeNode* root, int cur_sum, int target) {

        if (root == NULL) return false;

        cur_sum = cur_sum + root->val;

        if (cur_sum == target && root->left == NULL && root->right == NULL) return true;

        if (dfs(root->left, cur_sum, target)) return true;

        if (dfs(root->right, cur_sum, target)) return true;

        return false;

    }

};

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