112. Path Sum

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    bool solve(TreeNode* root, int targetSum, int sum)
    {
        if(root == NULL)
            return false;
        
        sum += root -> val;

        if(sum == targetSum && !root -> left && !root -> right)
            return true;
        bool left =  solve(root -> left, targetSum, sum);
        bool right = solve(root -> right, targetSum, sum);

        return left || right;

    }

    bool hasPathSum(TreeNode* root, int targetSum) {
        return solve(root, targetSum, 0);
    }
};